mailUsers

Mail Users. Mail-enabled accounts with an external address but no mailbox. The mailUsers entity set lives under /exchange/v1.0/mailUsers in the Recipients category.

Fact	Value
Path	`/exchange/v1.0/mailUsers`
Category	Recipients
Tier	Tier 0, Directory
Read role	`Recipient.Read.All` (Community)
Write role	`Recipient.ReadWrite.All` (Pro)
Backing cmdlets	Get-MailUser, Set-MailUser, New-MailUser, Remove-MailUser

Routes

Method	Path	Synopsis	Role	Plan
GET	`/exchange/v1.0/mailUsers`	List mailUsers entries.	`Recipient.Read`	Community
POST	`/exchange/v1.0/mailUsers`	POST /mailUsers - creates a mail-enabled user via New-MailUser. One of externalEmailAddress / microsoftOnlineServicesID + password / federatedIdentity must be present (cmdlet enforces the parameter-set mutex). password is plain-text in the body, converted to SecureString server-side per the slice-6 pattern. Returns 201 + Location.	`Recipient.ReadWrite`	Pro
GET	`/exchange/v1.0/mailUsers/{key}`	Get a single mailUsers entry by Identity.	`Recipient.Read`	Community
PATCH	`/exchange/v1.0/mailUsers/{key}`	PATCH /mailUsers/{key} - partial update via Set-MailUser. Returns 200 + updated entity.	`Recipient.ReadWrite`	Pro
DELETE	`/exchange/v1.0/mailUsers/{key}`	DELETE /mailUsers/{key} - destructive. Use ?permanentlyDelete=true to skip the recoverable-items window.	`Recipient.ReadWrite`	Pro

GET /exchange/v1.0/mailUsers

List mailUsers entries.

Backing cmdlet: Get-MailUser. Role: Recipient.Read (Community).

Parameter	In	Type	Description
`softDeletedMailUser`	query	bool (switch)	Include soft-deleted (still-recoverable) mail users in the results (EXO-only, maps -SoftDeletedMailUser).
`sharedWithMailUser`	query	bool (switch)	List shared mail users in the results (EXO-only, maps -SharedWithMailUser).
`all`	query	bool (switch)	Return all results instead of the EXO default of 1000. Maps -ResultSize Unlimited on Get-MailUser; prevents silent truncation in large tenants.
`anr`	query	string	Ambiguous name resolution: match mail users by partial name, display name, or alias. Maps -Anr on Get-MailUser.
`hVEAccount`	query	bool (switch)	Return only high-volume email (HVE) accounts in the results. Maps -HVEAccount on Get-MailUser.

List mailUsers

Returns the first three mail users in the organization. Backed by the Get-MailUser cmdlet; each entry is the full MailUser entity including guest and cloud mail-user variants.

GET /exchange/v1.0/mailUsers?$top=3 HTTP/1.1
Authorization: Bearer {token}

HTTP/1.1 200 OK

{
  "@odata.context": "http://localhost:5043/exchange/v1.0/$metadata#mailUsers",
  "value": [
    {
      "Id": "19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4",
      "ExchangeGuid": "00000000-0000-0000-0000-000000000000",
      "Guid": "23078dde-6e0e-40a0-a9f7-779c3299b9a2",
      "DisplayName": "Carter, Sam",
      "SimpleDisplayName": "",
      "PhoneticDisplayName": null,
      "Name": "19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4",
      "Alias": "sam.carter_contoso.com#EXT#",
      "DistinguishedName": "CN=19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4,OU=contoso.onmicrosoft.com,OU=Microsoft Exchange Hosted Organizations,DC=EURPR01A017,DC=PROD,DC=OUTLOOK,DC=COM",
      "Identity": "19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4",
      "ExternalDirectoryObjectId": "19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4",
      "PrimarySmtpAddress": "sam.carter@contoso.com",
      "WindowsLiveID": "sam.carter_contoso.com#EXT#@contoso.onmicrosoft.com",
      "WindowsEmailAddress": "",
      "EmailAddresses": [
        "SMTP:sam.carter@contoso.com"
      ],
      "EmailAddressPolicyEnabled": false,
      "RecipientType": "MailUser",
      "RecipientTypeDetails": "GuestMailUser",
      "OrganizationalUnit": "eurpr01a017.prod.outlook.com/Microsoft Exchange Hosted Organizations/contoso.onmicrosoft.com",
      "OrganizationId": "EURPR01A017.PROD.OUTLOOK.COM/Microsoft Exchange Hosted Organizations/contoso.onmicrosoft.com - EURPR01A017.PROD.OUTLOOK.COM/ConfigurationUnits/contoso.onmicrosoft.com/Configuration",
      "CustomAttribute1": "",
      "CustomAttribute2": "",
      "CustomAttribute3": "",
      "CustomAttribute4": "",
      "CustomAttribute5": "",
      "ExtensionCustomAttribute1": [],
      "ExtensionCustomAttribute2": [],
      "ExtensionCustomAttribute3": [],
      "ExtensionCustomAttribute4": [],
      "ExtensionCustomAttribute5": [],
      "HiddenFromAddressListsEnabled": true,
      "AddressBookPolicy": null,
      "WhenCreated": "2026-05-15T22:55:35+03:00",
      "WhenChanged": "2026-05-15T23:43:13+03:00",
      "WhenCreatedUTC": "2026-05-15T19:55:35Z",
      "WhenChangedUTC": "2026-05-15T20:43:13Z",
      "ExternalEmailAddress": "SMTP:sam.carter@contoso.com",
      "UserPrincipalName": "sam.carter_contoso.com#EXT#@contoso.onmicrosoft.com",
      "FirstName": null,
      "LastName": null,
      "Title": null,
      "Department": null,
      "Company": null,
      "Office": null,
      "Phone": null,
      "MobilePhone": null,
      "Manager": null,
      "City": null,
      "StateOrProvince": null,
      "PostalCode": null,
      "CountryOrRegion": null,
      "AccountDisabled": false,
      "ExternalDirectoryObjectIdSet": false,
      "SamAccountName": "$JMVGI0-ND6TQ7JPC5HT",
      "AcceptMessagesOnlyFrom": [],
      "AcceptMessagesOnlyFromDLMembers": [],
      "AcceptMessagesOnlyFromSendersOrMembers": [],
      "AddressListMembership": [
        "\\All Mail Users(VLV)",
        "\\All Recipients(VLV)"
      ],
      "AdministrativeUnits": [],
      "AgentIdentityBlueprintId": "",
      "AggregatedMailboxGuids": [],
      "ArbitrationMailbox": null,
      "ArchiveDatabase": null,
      "ArchiveGuid": "00000000-0000-0000-0000-000000000000",
      "ArchiveName": [],
      "ArchiveQuota": "100 GB (107,374,182,400 bytes)",
      "ArchiveRelease": "",
      "ArchiveStatus": "None",
      "ArchiveWarningQuota": "90 GB (96,636,764,160 bytes)",
      "BulkMailEnabled": false,
      "BypassModerationFromSendersOrMembers": [],
      "CalendarVersionStoreDisabled": false,
      "ComplianceTagHoldApplied": false,
      "CustomAttribute10": "",
      "CustomAttribute11": "",
      "CustomAttribute12": "",
      "CustomAttribute13": "",
      "CustomAttribute14": "",
      "CustomAttribute15": "",
      "CustomAttribute6": "",
      "CustomAttribute7": "",
      "CustomAttribute8": "",
      "CustomAttribute9": "",
      "DataEncryptionPolicy": null,
      "DelayHoldApplied": false,
      "DelayReleaseHoldApplied": false,
      "DeliverToMailboxAndForward": false,
      "DisabledArchiveDatabase": null,
      "DisabledArchiveGuid": "00000000-0000-0000-0000-000000000000",
      "EndDateForRetentionHold": null,
      "ExchangeObjectId": "05aeb349-a264-492c-90cc-213efeaec4a0",
      "ForwardingAddress": null,
      "GrantSendOnBehalfTo": [],
      "GuestHint": null,
      "GuestInfo": null,
      "HasPicture": false,
      "HasSpokenName": false,
      "ImmutableId": "",
      "InactiveMailboxRetireTime": null,
      "IsAgenticUser": false,
      "IsDirSynced": false,
      "IsInactiveMailbox": false,
      "IsMonitoringMailbox": false,
      "IsSoftDeletedByDisable": false,
      "IsSoftDeletedByRemove": false,
      "IssueWarningQuota": "98 GB (105,226,698,752 bytes)",
      "JoinedSmtpAddress": "",
      "JournalArchiveAddress": "",
      "LastExchangeChangedTime": null,
      "LegacyExchangeDN": "/o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=c72fefb7b5254d28864ce50da237c9c2-19ace2d2-ce",
      "LitigationHoldDate": null,
      "LitigationHoldEnabled": false,
      "LitigationHoldOwner": "",
      "MacAttachmentFormat": "BinHex",
      "MailTip": null,
      "MailTipTranslations": [],
      "MailboxContainerGuid": null,
      "MailboxLocations": [
        "1;7f26dee3-229d-48c8-98de-a333621a7cff;ComponentShared;EURPRD02.PROD.OUTLOOK.COM;fb6048e3-a9e3-418b-937c-d621c7c8276a"
      ],
      "MailboxMoveBatchName": "",
      "MailboxMoveFlags": "None",
      "MailboxMoveRemoteHostName": "",
      "MailboxMoveSourceMDB": null,
      "MailboxMoveStatus": "None",
      "MailboxMoveTargetMDB": null,
      "MailboxProvisioningConstraint": null,
      "MailboxProvisioningPreferences": [],
      "MailboxRegion": null,
      "MailboxRegionLastUpdateTime": null,
      "MailboxRegionSuffix": "None",
      "MailboxRelease": "",
      "MaxReceiveSize": "Unlimited",
      "MaxSendSize": "Unlimited",
      "MessageBodyFormat": "TextAndHtml",
      "MessageFormat": "Mime",
      "MicrosoftOnlineServicesID": "sam.carter_contoso.com#EXT#@contoso.onmicrosoft.com",
      "ModeratedBy": [],
      "ModerationEnabled": false,
      "NetID": "10032005E5A35A02",
      "OrganizationalUnitRoot": "contoso.onmicrosoft.com",
      "OrphanSoftDeleteTrackingTime": null,
      "OtherMail": "sam.carter@contoso.com",
      "PersistedCapabilities": [],
      "PoliciesExcluded": [
        "{26491cfc-9e50-4857-861b-0cb8df22b5d7}"
      ],
      "PoliciesIncluded": [],
      "ProhibitSendQuota": "99 GB (106,300,440,576 bytes)",
      "ProhibitSendReceiveQuota": "100 GB (107,374,182,400 bytes)",
      "ProtocolSettings": [
        "RemotePowerShell§1"
      ],
      "RecipientLimits": "Unlimited",
      "RecoverableItemsQuota": "30 GB (32,212,254,720 bytes)",
      "RecoverableItemsWarningQuota": "20 GB (21,474,836,480 bytes)",
      "RejectMessagesFrom": [],
      "RejectMessagesFromDLMembers": [],
      "RejectMessagesFromSendersOrMembers": [],
      "RequireSenderAuthenticationEnabled": false,
      "ResetPasswordOnNextLogon": false,
      "RetainDeletedItemsFor": "14.00:00:00",
      "RetentionComment": "",
      "RetentionHoldEnabled": false,
      "RetentionUrl": "",
      "SKUAssigned": null,
      "SendModerationNotifications": "Always",
      "SharedWithReference": "",
      "SingleItemRecoveryEnabled": false,
      "StartDateForRetentionHold": null,
      "StsRefreshTokensValidFrom": "2026-05-15T22:55:17+03:00",
      "UMDtmfMap": [],
      "UsageLocation": null,
      "UseMapiRichTextFormat": "Never",
      "UsePreferMessageFormat": false,
      "UserCertificate": [],
      "UserIdentityParent": "",
      "UserSMimeCertificate": [],
      "WasInactiveMailbox": false,
      "WhenMailboxCreated": null,
      "WhenSoftDeleted": null,
      "ExchangeUserAccountControl": "NormalAccount",
      "InPlaceHolds": []
    },
    {
      "Id": "7ff1b46c-a344-468c-86b8-7babac43d16b",
      "ExchangeGuid": "00000000-0000-0000-0000-000000000000",
      "Guid": "b78f5310-a5c4-4259-b03f-88bd44b6df61",
      "DisplayName": "Lee, Dana",
      "SimpleDisplayName": "",
      "PhoneticDisplayName": null,
      "Name": "7ff1b46c-a344-468c-86b8-7babac43d16b",
      "Alias": "dana.lee_contoso.com#EXT#",
      "DistinguishedName": "CN=7ff1b46c-a344-468c-86b8-7babac43d16b,OU=contoso.onmicrosoft.com,OU=Microsoft Exchange Hosted Organizations,DC=EURPR01A017,DC=PROD,DC=OUTLOOK,DC=COM",
      "Identity": "7ff1b46c-a344-468c-86b8-7babac43d16b",
      "ExternalDirectoryObjectId": "7ff1b46c-a344-468c-86b8-7babac43d16b",
      "PrimarySmtpAddress": "dana.lee@contoso.com",
      "WindowsLiveID": "dana.lee_contoso.com#EXT#@contoso.onmicrosoft.com",
      "WindowsEmailAddress": "",
      "EmailAddresses": [
        "SMTP:dana.lee@contoso.com"
      ],
      "EmailAddressPolicyEnabled": false,
      "RecipientType": "MailUser",
      "RecipientTypeDetails": "GuestMailUser",
      "OrganizationalUnit": "eurpr01a017.prod.outlook.com/Microsoft Exchange Hosted Organizations/contoso.onmicrosoft.com",
      "OrganizationId": "EURPR01A017.PROD.OUTLOOK.COM/Microsoft Exchange Hosted Organizations/contoso.onmicrosoft.com - EURPR01A017.PROD.OUTLOOK.COM/ConfigurationUnits/contoso.onmicrosoft.com/Configuration",
      "CustomAttribute1": "",
      "CustomAttribute2": "",
      "CustomAttribute3": "",
      "CustomAttribute4": "",
      "CustomAttribute5": "",
      "ExtensionCustomAttribute1": [],
      "ExtensionCustomAttribute2": [],
      "ExtensionCustomAttribute3": [],
      "ExtensionCustomAttribute4": [],
      "ExtensionCustomAttribute5": [],
      "HiddenFromAddressListsEnabled": true,
      "AddressBookPolicy": null,
      "WhenCreated": "2026-03-31T17:41:03+03:00",
      "WhenChanged": "2026-05-29T07:33:07+03:00",
      "WhenCreatedUTC": "2026-03-31T14:41:03Z",
      "WhenChangedUTC": "2026-05-29T04:33:07Z",
      "ExternalEmailAddress": "SMTP:dana.lee@contoso.com",
      "UserPrincipalName": "dana.lee_contoso.com#EXT#@contoso.onmicrosoft.com",
      "FirstName": null,
      "LastName": null,
      "Title": null,
      "Department": null,
      "Company": null,
      "Office": null,
      "Phone": null,
      "MobilePhone": null,
      "Manager": null,
      "City": null,
      "StateOrProvince": null,
      "PostalCode": null,
      "CountryOrRegion": null,
      "AccountDisabled": false,
      "ExternalDirectoryObjectIdSet": false,
      "SamAccountName": "$2QUJH0-79D83LH534U7",
      "AcceptMessagesOnlyFrom": [],
      "AcceptMessagesOnlyFromDLMembers": [],
      "AcceptMessagesOnlyFromSendersOrMembers": [],
      "AddressListMembership": [
        "\\All Recipients(VLV)",
        "\\All Mail Users(VLV)"
      ],
      "AdministrativeUnits": [],
      "AgentIdentityBlueprintId": "",
      "AggregatedMailboxGuids": [],
      "ArbitrationMailbox": null,
      "ArchiveDatabase": null,
      "ArchiveGuid": "00000000-0000-0000-0000-000000000000",
      "ArchiveName": [],
      "ArchiveQuota": "100 GB (107,374,182,400 bytes)",
      "ArchiveRelease": "",
      "ArchiveStatus": "None",
      "ArchiveWarningQuota": "90 GB (96,636,764,160 bytes)",
      "BulkMailEnabled": false,
      "BypassModerationFromSendersOrMembers": [],
      "CalendarVersionStoreDisabled": false,
      "ComplianceTagHoldApplied": false,
      "CustomAttribute10": "",
      "CustomAttribute11": "",
      "CustomAttribute12": "",
      "CustomAttribute13": "",
      "CustomAttribute14": "",
      "CustomAttribute15": "",
      "CustomAttribute6": "",
      "CustomAttribute7": "",
      "CustomAttribute8": "",
      "CustomAttribute9": "",
      "DataEncryptionPolicy": null,
      "DelayHoldApplied": false,
      "DelayReleaseHoldApplied": false,
      "DeliverToMailboxAndForward": false,
      "DisabledArchiveDatabase": null,
      "DisabledArchiveGuid": "00000000-0000-0000-0000-000000000000",
      "EndDateForRetentionHold": null,
      "ExchangeObjectId": "f8f7082b-f8ff-43e7-b992-f1edde58bc12",
      "ForwardingAddress": null,
      "GrantSendOnBehalfTo": [],
      "GuestHint": null,
      "GuestInfo": null,
      "HasPicture": false,
      "HasSpokenName": false,
      "ImmutableId": "",
      "InactiveMailboxRetireTime": null,
      "IsAgenticUser": false,
      "IsDirSynced": false,
      "IsInactiveMailbox": false,
      "IsMonitoringMailbox": false,
      "IsSoftDeletedByDisable": false,
      "IsSoftDeletedByRemove": false,
      "IssueWarningQuota": "98 GB (105,226,698,752 bytes)",
      "JoinedSmtpAddress": "",
      "JournalArchiveAddress": "",
      "LastExchangeChangedTime": null,
      "LegacyExchangeDN": "/o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=b70cf7fc96c644b38b3b99857145e693-7ff1b46c-a3",
      "LitigationHoldDate": null,
      "LitigationHoldEnabled": false,
      "LitigationHoldOwner": "",
      "MacAttachmentFormat": "BinHex",
      "MailTip": null,
      "MailTipTranslations": [],
      "MailboxContainerGuid": null,
      "MailboxLocations": [
        "1;ba6fdb99-20e9-4083-bcf9-bd23d2c3821f;ComponentShared;eurprd02.prod.outlook.com;e362720a-264d-4472-8f6b-ccc785dbfa63"
      ],
      "MailboxMoveBatchName": "",
      "MailboxMoveFlags": "None",
      "MailboxMoveRemoteHostName": "",
      "MailboxMoveSourceMDB": null,
      "MailboxMoveStatus": "None",
      "MailboxMoveTargetMDB": null,
      "MailboxProvisioningConstraint": null,
      "MailboxProvisioningPreferences": [],
      "MailboxRegion": null,
      "MailboxRegionLastUpdateTime": null,
      "MailboxRegionSuffix": "None",
      "MailboxRelease": "",
      "MaxReceiveSize": "Unlimited",
      "MaxSendSize": "Unlimited",
      "MessageBodyFormat": "TextAndHtml",
      "MessageFormat": "Mime",
      "MicrosoftOnlineServicesID": "dana.lee_contoso.com#EXT#@contoso.onmicrosoft.com",
      "ModeratedBy": [],
      "ModerationEnabled": false,
      "NetID": "1003200567831E8A",
      "OrganizationalUnitRoot": "contoso.onmicrosoft.com",
      "OrphanSoftDeleteTrackingTime": null,
      "OtherMail": "dana.lee@contoso.com",
      "PersistedCapabilities": [],
      "PoliciesExcluded": [
        "{26491cfc-9e50-4857-861b-0cb8df22b5d7}"
      ],
      "PoliciesIncluded": [],
      "ProhibitSendQuota": "99 GB (106,300,440,576 bytes)",
      "ProhibitSendReceiveQuota": "100 GB (107,374,182,400 bytes)",
      "ProtocolSettings": [
        "RemotePowerShell§1"
      ],
      "RecipientLimits": "Unlimited",
      "RecoverableItemsQuota": "100 GB (107,374,182,400 bytes)",
      "RecoverableItemsWarningQuota": "90 GB (96,636,764,160 bytes)",
      "RejectMessagesFrom": [],
      "RejectMessagesFromDLMembers": [],
      "RejectMessagesFromSendersOrMembers": [],
      "RequireSenderAuthenticationEnabled": false,
      "ResetPasswordOnNextLogon": false,
      "RetainDeletedItemsFor": "14.00:00:00",
      "RetentionComment": "",
      "RetentionHoldEnabled": false,
      "RetentionUrl": "",
      "SKUAssigned": null,
      "SendModerationNotifications": "Always",
      "SharedWithReference": "",
      "SingleItemRecoveryEnabled": false,
      "StartDateForRetentionHold": null,
      "StsRefreshTokensValidFrom": "2025-12-11T13:00:48+02:00",
      "UMDtmfMap": [],
      "UsageLocation": null,
      "UseMapiRichTextFormat": "Never",
      "UsePreferMessageFormat": false,
      "UserCertificate": [],
      "UserIdentityParent": "",
      "UserSMimeCertificate": [],
      "WasInactiveMailbox": false,
      "WhenMailboxCreated": null,
      "WhenSoftDeleted": null,
      "ExchangeUserAccountControl": "NormalAccount",
      "InPlaceHolds": []
    },
    {
      "Id": "90678a00-1c81-4d40-a59d-4ea05d064948",
      "ExchangeGuid": "00000000-0000-0000-0000-000000000000",
      "Guid": "0c1abe7a-cb34-4b5f-86b2-933a40f34e18",
      "DisplayName": "t1",
      "SimpleDisplayName": "",
      "PhoneticDisplayName": null,
      "Name": "90678a00-1c81-4d40-a59d-4ea05d064948",
      "Alias": "ffs",
      "DistinguishedName": "CN=90678a00-1c81-4d40-a59d-4ea05d064948,OU=contoso.onmicrosoft.com,OU=Microsoft Exchange Hosted Organizations,DC=EURPR01A017,DC=PROD,DC=OUTLOOK,DC=COM",
      "Identity": "90678a00-1c81-4d40-a59d-4ea05d064948",
      "ExternalDirectoryObjectId": "90678a00-1c81-4d40-a59d-4ea05d064948",
      "PrimarySmtpAddress": "ffs@contoso.onmicrosoft.com",
      "WindowsLiveID": "ffs@contoso.onmicrosoft.com",
      "WindowsEmailAddress": "ffs@contoso.onmicrosoft.com",
      "EmailAddresses": [
        "SMTP:ffs@contoso.onmicrosoft.com"
      ],
      "EmailAddressPolicyEnabled": false,
      "RecipientType": "MailUser",
      "RecipientTypeDetails": "MailUser",
      "OrganizationalUnit": "eurpr01a017.prod.outlook.com/Microsoft Exchange Hosted Organizations/contoso.onmicrosoft.com",
      "OrganizationId": "EURPR01A017.PROD.OUTLOOK.COM/Microsoft Exchange Hosted Organizations/contoso.onmicrosoft.com - EURPR01A017.PROD.OUTLOOK.COM/ConfigurationUnits/contoso.onmicrosoft.com/Configuration",
      "CustomAttribute1": "",
      "CustomAttribute2": "",
      "CustomAttribute3": "",
      "CustomAttribute4": "",
      "CustomAttribute5": "",
      "ExtensionCustomAttribute1": [],
      "ExtensionCustomAttribute2": [],
      "ExtensionCustomAttribute3": [],
      "ExtensionCustomAttribute4": [],
      "ExtensionCustomAttribute5": [],
      "HiddenFromAddressListsEnabled": true,
      "AddressBookPolicy": null,
      "WhenCreated": "2026-03-30T17:10:28+03:00",
      "WhenChanged": "2026-03-30T17:49:40+03:00",
      "WhenCreatedUTC": "2026-03-30T14:10:28Z",
      "WhenChangedUTC": "2026-03-30T14:49:40Z",
      "ExternalEmailAddress": "SMTP:admin@contoso.onmicrosoft.com",
      "UserPrincipalName": "ffs@contoso.onmicrosoft.com",
      "FirstName": null,
      "LastName": null,
      "Title": null,
      "Department": null,
      "Company": null,
      "Office": null,
      "Phone": null,
      "MobilePhone": null,
      "Manager": null,
      "City": null,
      "StateOrProvince": null,
      "PostalCode": null,
      "CountryOrRegion": null,
      "AccountDisabled": false,
      "ExternalDirectoryObjectIdSet": false,
      "SamAccountName": "$I88HG0-R9311HD5EO9K",
      "AcceptMessagesOnlyFrom": [],
      "AcceptMessagesOnlyFromDLMembers": [],
      "AcceptMessagesOnlyFromSendersOrMembers": [],
      "AddressListMembership": [
        "\\All Recipients(VLV)",
        "\\All Mail Users(VLV)"
      ],
      "AdministrativeUnits": [],
      "AgentIdentityBlueprintId": "",
      "AggregatedMailboxGuids": [],
      "ArbitrationMailbox": null,
      "ArchiveDatabase": null,
      "ArchiveGuid": "00000000-0000-0000-0000-000000000000",
      "ArchiveName": [],
      "ArchiveQuota": "100 GB (107,374,182,400 bytes)",
      "ArchiveRelease": "",
      "ArchiveStatus": "None",
      "ArchiveWarningQuota": "90 GB (96,636,764,160 bytes)",
      "BulkMailEnabled": false,
      "BypassModerationFromSendersOrMembers": [],
      "CalendarVersionStoreDisabled": false,
      "ComplianceTagHoldApplied": false,
      "CustomAttribute10": "",
      "CustomAttribute11": "",
      "CustomAttribute12": "",
      "CustomAttribute13": "",
      "CustomAttribute14": "",
      "CustomAttribute15": "",
      "CustomAttribute6": "",
      "CustomAttribute7": "",
      "CustomAttribute8": "",
      "CustomAttribute9": "",
      "DataEncryptionPolicy": null,
      "DelayHoldApplied": false,
      "DelayReleaseHoldApplied": false,
      "DeliverToMailboxAndForward": false,
      "DisabledArchiveDatabase": null,
      "DisabledArchiveGuid": "00000000-0000-0000-0000-000000000000",
      "EndDateForRetentionHold": null,
      "ExchangeObjectId": "9b895e64-643d-4786-97de-6e1206e4b47e",
      "ForwardingAddress": null,
      "GrantSendOnBehalfTo": [],
      "GuestHint": null,
      "GuestInfo": null,
      "HasPicture": false,
      "HasSpokenName": false,
      "ImmutableId": "",
      "InactiveMailboxRetireTime": null,
      "IsAgenticUser": false,
      "IsDirSynced": true,
      "IsInactiveMailbox": false,
      "IsMonitoringMailbox": false,
      "IsSoftDeletedByDisable": false,
      "IsSoftDeletedByRemove": false,
      "IssueWarningQuota": "98 GB (105,226,698,752 bytes)",
      "JoinedSmtpAddress": "",
      "JournalArchiveAddress": "",
      "LastExchangeChangedTime": null,
      "LegacyExchangeDN": "/o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=67d37309858a4664acab40cb33b54fff-90678a00-1c",
      "LitigationHoldDate": null,
      "LitigationHoldEnabled": false,
      "LitigationHoldOwner": "",
      "MacAttachmentFormat": "BinHex",
      "MailTip": null,
      "MailTipTranslations": [],
      "MailboxContainerGuid": null,
      "MailboxLocations": [
        "1;49bb6ff0-fa7d-422f-a782-570196719202;ComponentShared;eurprd02.prod.outlook.com;288a27b4-5ca1-49b6-af4e-308375684f6f"
      ],
      "MailboxMoveBatchName": "",
      "MailboxMoveFlags": "None",
      "MailboxMoveRemoteHostName": "",
      "MailboxMoveSourceMDB": null,
      "MailboxMoveStatus": "None",
      "MailboxMoveTargetMDB": null,
      "MailboxProvisioningConstraint": null,
      "MailboxProvisioningPreferences": [],
      "MailboxRegion": null,
      "MailboxRegionLastUpdateTime": null,
      "MailboxRegionSuffix": "None",
      "MailboxRelease": "",
      "MaxReceiveSize": "Unlimited",
      "MaxSendSize": "Unlimited",
      "MessageBodyFormat": "TextAndHtml",
      "MessageFormat": "Mime",
      "MicrosoftOnlineServicesID": "ffs@contoso.onmicrosoft.com",
      "ModeratedBy": [],
      "ModerationEnabled": false,
      "NetID": "100320044BA52B09",
      "OrganizationalUnitRoot": "contoso.onmicrosoft.com",
      "OrphanSoftDeleteTrackingTime": null,
      "OtherMail": null,
      "PersistedCapabilities": [],
      "PoliciesExcluded": [
        "{26491cfc-9e50-4857-861b-0cb8df22b5d7}"
      ],
      "PoliciesIncluded": [],
      "ProhibitSendQuota": "99 GB (106,300,440,576 bytes)",
      "ProhibitSendReceiveQuota": "100 GB (107,374,182,400 bytes)",
      "ProtocolSettings": [
        "RemotePowerShell§1"
      ],
      "RecipientLimits": "Unlimited",
      "RecoverableItemsQuota": "100 GB (107,374,182,400 bytes)",
      "RecoverableItemsWarningQuota": "90 GB (96,636,764,160 bytes)",
      "RejectMessagesFrom": [],
      "RejectMessagesFromDLMembers": [],
      "RejectMessagesFromSendersOrMembers": [],
      "RequireSenderAuthenticationEnabled": false,
      "ResetPasswordOnNextLogon": false,
      "RetainDeletedItemsFor": "14.00:00:00",
      "RetentionComment": "",
      "RetentionHoldEnabled": false,
      "RetentionUrl": "",
      "SKUAssigned": null,
      "SendModerationNotifications": "Always",
      "SharedWithReference": "",
      "SingleItemRecoveryEnabled": false,
      "StartDateForRetentionHold": null,
      "StsRefreshTokensValidFrom": "2025-02-10T20:06:17+02:00",
      "UMDtmfMap": [],
      "UsageLocation": null,
      "UseMapiRichTextFormat": "UseDefaultSettings",
      "UsePreferMessageFormat": false,
      "UserCertificate": [],
      "UserIdentityParent": "",
      "UserSMimeCertificate": [],
      "WasInactiveMailbox": false,
      "WhenMailboxCreated": null,
      "WhenSoftDeleted": null,
      "ExchangeUserAccountControl": "NormalAccount",
      "InPlaceHolds": [
        "UniH8bcbfdfd-77ad-4386-b0d2-72eb55fc0b33"
      ]
    }
  ]
}

Notes: Mixes GuestMailUser (external invitees, alias ends in #EXT#) and MailUser (cloud mail user) variants. Quota/limit strings are returned formatted by EXO.

POST /exchange/v1.0/mailUsers

POST /mailUsers - creates a mail-enabled user via New-MailUser. One of externalEmailAddress / microsoftOnlineServicesID + password / federatedIdentity must be present (cmdlet enforces the parameter-set mutex). password is plain-text in the body, converted to SecureString server-side per the slice-6 pattern. Returns 201 + Location.

Backing cmdlet: New-MailUser. Role: Recipient.ReadWrite (Pro).

Parameter	In	Type	Required
`name`	body		yes
`alias`	body
`displayName`	body
`externalEmailAddress`	body
`federatedIdentity`	body
`firstName`	body
`hveAccount`	body	boolean (switch)
`immutableId`	body
`initials`	body
`lastName`	body
`macAttachmentFormat`	body
`mailboxRegion`	body
`messageBodyFormat`	body
`messageFormat`	body
`microsoftOnlineServicesID`	body
`moderatedBy`	body
`moderationEnabled`	body
`organizationalUnit`	body
`password`	body
`primarySmtpAddress`	body
`remotePowerShellEnabled`	body
`sendModerationNotifications`	body
`usePreferMessageFormat`	body
`dryRun`	query	bool (switch)

Create a mail user without the required name (400)

New-MailUser requires the name field. Omitting it fails body validation before the cmdlet is invoked and returns the canonical 400 envelope.

POST /exchange/v1.0/mailUsers HTTP/1.1
Authorization: Bearer {token}
Content-Type: application/json

{
  "displayName": "Exonaut Sample MailUser",
  "externalEmailAddress": "exonaut.sample@contoso.com"
}

HTTP/1.1 400 Bad Request
Content-Type: application/json

{
  "error": {
    "code": "BadRequest",
    "message": "The 'name' field is required.",
    "target": "name"
  },
  "correlationId": "0HN7K2Q9F3B1A:00000001"
}

Notes: Doc-derived from Wiki + write-param allowlist; not live-captured. Body fields are Wiki-valid; values are illustrative.

Related: GET /exchange/v1.0/mailUsers

Create a mail user

Creates a mail-enabled user (no mailbox; mail is delivered to an external address) via New-MailUser. Name is required; supply one identity combo - externalEmailAddress, or microsoftOnlineServicesID + password, or federatedIdentity - and the cmdlet enforces the parameter-set mutex.

POST /exchange/v1.0/mailUsers HTTP/1.1
Authorization: Bearer {token}
Content-Type: application/json

{
  "name": "exonaut-sample-mailUsers",
  "displayName": "Exonaut Sample MailUser",
  "alias": "exonaut-sample-mailUsers",
  "firstName": "Exonaut",
  "lastName": "Sample",
  "externalEmailAddress": "exonaut.sample@contoso.com",
  "primarySmtpAddress": "exonaut-sample-mailUsers@contoso.com"
}

HTTP/1.1 201 Created
Location: /exchange/v1.0/mailUsers/exonaut-sample-mailUsers

{
  "Id": "exonaut-sample-mailUsers",
  "Identity": "exonaut-sample-mailUsers",
  "Name": "exonaut-sample-mailUsers",
  "DisplayName": "Exonaut Sample MailUser",
  "Alias": "exonaut-sample-mailUsers",
  "ExternalEmailAddress": "SMTP:exonaut.sample@contoso.com",
  "PrimarySmtpAddress": "exonaut-sample-mailUsers@contoso.com"
}

Notes: Doc-derived from Wiki + write-param allowlist; not live-captured. Body fields are Wiki-valid; values are illustrative.

Related: GET /exchange/v1.0/mailUsers

GET /exchange/v1.0/mailUsers/{key}

Get a single mailUsers entry by Identity.

Backing cmdlet: Get-MailUser. Role: Recipient.Read (Community).

Get a single mailUsers entry

Returns the full MailUser entity for one identity. Backed by Get-MailUser with -Identity {key}; the key resolves against ExternalDirectoryObjectId, alias, or primary SMTP.

GET /exchange/v1.0/mailUsers/{key} HTTP/1.1
Authorization: Bearer {token}

HTTP/1.1 200 OK

{
  "@odata.context": "http://localhost:5043/exchange/v1.0/$metadata#mailUsers/$entity",
  "Id": "19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4",
  "ExchangeGuid": "00000000-0000-0000-0000-000000000000",
  "Guid": "23078dde-6e0e-40a0-a9f7-779c3299b9a2",
  "DisplayName": "Carter, Sam",
  "SimpleDisplayName": "",
  "PhoneticDisplayName": null,
  "Name": "19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4",
  "Alias": "sam.carter_contoso.com#EXT#",
  "DistinguishedName": "CN=19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4,OU=contoso.onmicrosoft.com,OU=Microsoft Exchange Hosted Organizations,DC=EURPR01A017,DC=PROD,DC=OUTLOOK,DC=COM",
  "Identity": "19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4",
  "ExternalDirectoryObjectId": "19ace2d2-ceaf-4ddf-a6c9-08ddb9eab4a4",
  "PrimarySmtpAddress": "sam.carter@contoso.com",
  "WindowsLiveID": "sam.carter_contoso.com#EXT#@contoso.onmicrosoft.com",
  "WindowsEmailAddress": "",
  "EmailAddresses": [
    "SMTP:sam.carter@contoso.com"
  ],
  "EmailAddressPolicyEnabled": false,
  "RecipientType": "MailUser",
  "RecipientTypeDetails": "GuestMailUser",
  "OrganizationalUnit": "eurpr01a017.prod.outlook.com/Microsoft Exchange Hosted Organizations/contoso.onmicrosoft.com",
  "OrganizationId": "EURPR01A017.PROD.OUTLOOK.COM/Microsoft Exchange Hosted Organizations/contoso.onmicrosoft.com - EURPR01A017.PROD.OUTLOOK.COM/ConfigurationUnits/contoso.onmicrosoft.com/Configuration",
  "CustomAttribute1": "",
  "CustomAttribute2": "",
  "CustomAttribute3": "",
  "CustomAttribute4": "",
  "CustomAttribute5": "",
  "ExtensionCustomAttribute1": [],
  "ExtensionCustomAttribute2": [],
  "ExtensionCustomAttribute3": [],
  "ExtensionCustomAttribute4": [],
  "ExtensionCustomAttribute5": [],
  "HiddenFromAddressListsEnabled": true,
  "AddressBookPolicy": null,
  "WhenCreated": "2026-05-15T22:55:35+03:00",
  "WhenChanged": "2026-05-15T23:43:13+03:00",
  "WhenCreatedUTC": "2026-05-15T19:55:35Z",
  "WhenChangedUTC": "2026-05-15T20:43:13Z",
  "ExternalEmailAddress": "SMTP:sam.carter@contoso.com",
  "UserPrincipalName": "sam.carter_contoso.com#EXT#@contoso.onmicrosoft.com",
  "FirstName": null,
  "LastName": null,
  "Title": null,
  "Department": null,
  "Company": null,
  "Office": null,
  "Phone": null,
  "MobilePhone": null,
  "Manager": null,
  "City": null,
  "StateOrProvince": null,
  "PostalCode": null,
  "CountryOrRegion": null,
  "AccountDisabled": false,
  "ExternalDirectoryObjectIdSet": false,
  "SamAccountName": "$JMVGI0-ND6TQ7JPC5HT",
  "AcceptMessagesOnlyFrom": [],
  "AcceptMessagesOnlyFromDLMembers": [],
  "AcceptMessagesOnlyFromSendersOrMembers": [],
  "AddressListMembership": [
    "\\All Mail Users(VLV)",
    "\\All Recipients(VLV)"
  ],
  "AdministrativeUnits": [],
  "AgentIdentityBlueprintId": "",
  "AggregatedMailboxGuids": [],
  "ArbitrationMailbox": null,
  "ArchiveDatabase": null,
  "ArchiveGuid": "00000000-0000-0000-0000-000000000000",
  "ArchiveName": [],
  "ArchiveQuota": "100 GB (107,374,182,400 bytes)",
  "ArchiveRelease": "",
  "ArchiveStatus": "None",
  "ArchiveWarningQuota": "90 GB (96,636,764,160 bytes)",
  "BulkMailEnabled": false,
  "BypassModerationFromSendersOrMembers": [],
  "CalendarVersionStoreDisabled": false,
  "ComplianceTagHoldApplied": false,
  "CustomAttribute10": "",
  "CustomAttribute11": "",
  "CustomAttribute12": "",
  "CustomAttribute13": "",
  "CustomAttribute14": "",
  "CustomAttribute15": "",
  "CustomAttribute6": "",
  "CustomAttribute7": "",
  "CustomAttribute8": "",
  "CustomAttribute9": "",
  "DataEncryptionPolicy": null,
  "DelayHoldApplied": false,
  "DelayReleaseHoldApplied": false,
  "DeliverToMailboxAndForward": false,
  "DisabledArchiveDatabase": null,
  "DisabledArchiveGuid": "00000000-0000-0000-0000-000000000000",
  "EndDateForRetentionHold": null,
  "ExchangeObjectId": "05aeb349-a264-492c-90cc-213efeaec4a0",
  "ForwardingAddress": null,
  "GrantSendOnBehalfTo": [],
  "GuestHint": null,
  "GuestInfo": null,
  "HasPicture": false,
  "HasSpokenName": false,
  "ImmutableId": "",
  "InactiveMailboxRetireTime": null,
  "IsAgenticUser": false,
  "IsDirSynced": false,
  "IsInactiveMailbox": false,
  "IsMonitoringMailbox": false,
  "IsSoftDeletedByDisable": false,
  "IsSoftDeletedByRemove": false,
  "IssueWarningQuota": "98 GB (105,226,698,752 bytes)",
  "JoinedSmtpAddress": "",
  "JournalArchiveAddress": "",
  "LastExchangeChangedTime": null,
  "LegacyExchangeDN": "/o=ExchangeLabs/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn=c72fefb7b5254d28864ce50da237c9c2-19ace2d2-ce",
  "LitigationHoldDate": null,
  "LitigationHoldEnabled": false,
  "LitigationHoldOwner": "",
  "MacAttachmentFormat": "BinHex",
  "MailTip": null,
  "MailTipTranslations": [],
  "MailboxContainerGuid": null,
  "MailboxLocations": [
    "1;7f26dee3-229d-48c8-98de-a333621a7cff;ComponentShared;EURPRD02.PROD.OUTLOOK.COM;fb6048e3-a9e3-418b-937c-d621c7c8276a"
  ],
  "MailboxMoveBatchName": "",
  "MailboxMoveFlags": "None",
  "MailboxMoveRemoteHostName": "",
  "MailboxMoveSourceMDB": null,
  "MailboxMoveStatus": "None",
  "MailboxMoveTargetMDB": null,
  "MailboxProvisioningConstraint": null,
  "MailboxProvisioningPreferences": [],
  "MailboxRegion": null,
  "MailboxRegionLastUpdateTime": null,
  "MailboxRegionSuffix": "None",
  "MailboxRelease": "",
  "MaxReceiveSize": "Unlimited",
  "MaxSendSize": "Unlimited",
  "MessageBodyFormat": "TextAndHtml",
  "MessageFormat": "Mime",
  "MicrosoftOnlineServicesID": "sam.carter_contoso.com#EXT#@contoso.onmicrosoft.com",
  "ModeratedBy": [],
  "ModerationEnabled": false,
  "NetID": "10032005E5A35A02",
  "OrganizationalUnitRoot": "contoso.onmicrosoft.com",
  "OrphanSoftDeleteTrackingTime": null,
  "OtherMail": "sam.carter@contoso.com",
  "PersistedCapabilities": [],
  "PoliciesExcluded": [
    "{26491cfc-9e50-4857-861b-0cb8df22b5d7}"
  ],
  "PoliciesIncluded": [],
  "ProhibitSendQuota": "99 GB (106,300,440,576 bytes)",
  "ProhibitSendReceiveQuota": "100 GB (107,374,182,400 bytes)",
  "ProtocolSettings": [
    "RemotePowerShell§1"
  ],
  "RecipientLimits": "Unlimited",
  "RecoverableItemsQuota": "30 GB (32,212,254,720 bytes)",
  "RecoverableItemsWarningQuota": "20 GB (21,474,836,480 bytes)",
  "RejectMessagesFrom": [],
  "RejectMessagesFromDLMembers": [],
  "RejectMessagesFromSendersOrMembers": [],
  "RequireSenderAuthenticationEnabled": false,
  "ResetPasswordOnNextLogon": false,
  "RetainDeletedItemsFor": "14.00:00:00",
  "RetentionComment": "",
  "RetentionHoldEnabled": false,
  "RetentionUrl": "",
  "SKUAssigned": null,
  "SendModerationNotifications": "Always",
  "SharedWithReference": "",
  "SingleItemRecoveryEnabled": false,
  "StartDateForRetentionHold": null,
  "StsRefreshTokensValidFrom": "2026-05-15T22:55:17+03:00",
  "UMDtmfMap": [],
  "UsageLocation": null,
  "UseMapiRichTextFormat": "Never",
  "UsePreferMessageFormat": false,
  "UserCertificate": [],
  "UserIdentityParent": "",
  "UserSMimeCertificate": [],
  "WasInactiveMailbox": false,
  "WhenMailboxCreated": null,
  "WhenSoftDeleted": null,
  "ExchangeUserAccountControl": "NormalAccount",
  "InPlaceHolds": []
}

Notes: GuestMailUser variant (external invitee): the alias and UPN carry the #EXT# suffix and ExternalEmailAddress points at the user’s home domain.

Related: GET /exchange/v1.0/mailUsers

Get a single mailUsers entry - not found

When the {key} does not resolve to any mail user (no matching ExternalDirectoryObjectId, alias, or SMTP address), Get-MailUser raises a not-found error which the middleware maps to a 404 with the canonical error envelope.

GET /exchange/v1.0/mailUsers/{key} HTTP/1.1
Authorization: Bearer {token}

HTTP/1.1 404 Not Found

{
  "error": {
    "code": "NotFound",
    "message": "Exchange object 'does-not-exist-12345' could not be found.",
    "target": "identity",
    "innerError": {
      "cmdlet": "Get-MailUser"
    }
  },
  "correlationId": "0HNLSU6PPVJ03:00000001"
}

Notes: The 404 is emitted by ExoExceptionMiddleware translating the cmdlet’s object-not-found error; correlationId is per-request.

PATCH /exchange/v1.0/mailUsers/{key}

PATCH /mailUsers/{key} - partial update via Set-MailUser. Returns 200 + updated entity.

Backing cmdlet: Set-MailUser. Role: Recipient.ReadWrite (Pro).

Parameter	In	Type
`acceptMessagesOnlyFrom`	body
`acceptMessagesOnlyFromDLMembers`	body
`acceptMessagesOnlyFromSendersOrMembers`	body
`alias`	body
`arbitrationMailbox`	body
`archiveGuid`	body
`archiveName`	body
`bypassModerationFromSendersOrMembers`	body
`createDTMFMap`	body
`customAttribute1`	body
`customAttribute10`	body
`customAttribute11`	body
`customAttribute12`	body
`customAttribute13`	body
`customAttribute14`	body
`customAttribute15`	body
`customAttribute2`	body
`customAttribute3`	body
`customAttribute4`	body
`customAttribute5`	body
`customAttribute6`	body
`customAttribute7`	body
`customAttribute8`	body
`customAttribute9`	body
`dataEncryptionPolicy`	body
`displayName`	body
`emailAddresses`	body
`emailAddressPolicyEnabled`	body
`exchangeGuid`	body
`excludeFromOrgHolds`	body
`extensionCustomAttribute1`	body
`extensionCustomAttribute2`	body
`extensionCustomAttribute3`	body
`extensionCustomAttribute4`	body
`extensionCustomAttribute5`	body
`externalEmailAddress`	body
`federatedIdentity`	body
`grantSendOnBehalfTo`	body
`hiddenFromAddressListsEnabled`	body
`immutableId`	body
`journalArchiveAddress`	body
`macAttachmentFormat`	body
`mailboxRegion`	body
`mailTip`	body
`mailTipTranslations`	body
`maxReceiveSize`	body
`maxSendSize`	body
`messageBodyFormat`	body
`messageFormat`	body
`microsoftOnlineServicesID`	body
`moderatedBy`	body
`moderationEnabled`	body
`name`	body
`password`	body
`primarySmtpAddress`	body
`recipientLimits`	body
`recoverableItemsQuota`	body
`recoverableItemsWarningQuota`	body
`rejectMessagesFrom`	body
`rejectMessagesFromDLMembers`	body
`rejectMessagesFromSendersOrMembers`	body
`removeOrphanedHolds`	body
`removePicture`	body	boolean (switch)
`removeSpokenName`	body	boolean (switch)
`requireSenderAuthenticationEnabled`	body
`resetPasswordOnNextLogon`	body
`samAccountName`	body
`secondaryAddress`	body
`secondaryDialPlan`	body
`sendModerationNotifications`	body
`simpleDisplayName`	body
`skipDualWrite`	body	boolean (switch)
`umDtmfMap`	body
`useMapiRichTextFormat`	body
`usePreferMessageFormat`	body
`userCertificate`	body
`userPrincipalName`	body
`userSMimeCertificate`	body
`windowsEmailAddress`	body
`dryRun`	query	bool (switch)

Update a mail user

Partial update of a mail-enabled user via Set-MailUser. Send only the fields you want to change; the controller fetches and returns the updated entity (200).

PATCH /exchange/v1.0/mailUsers/{key} HTTP/1.1
Authorization: Bearer {token}
Content-Type: application/json

{
  "displayName": "Exonaut Sample MailUser (Updated)",
  "mailTip": "This mailbox is an external mail user managed by Exonaut.",
  "hiddenFromAddressListsEnabled": true
}

HTTP/1.1 200 OK
Content-Type: application/json

{
  "Id": "exonaut-sample-mailUsers",
  "Identity": "exonaut-sample-mailUsers",
  "Name": "exonaut-sample-mailUsers",
  "DisplayName": "Exonaut Sample MailUser (Updated)",
  "MailTip": "This mailbox is an external mail user managed by Exonaut.",
  "HiddenFromAddressListsEnabled": true,
  "ExternalEmailAddress": "SMTP:exonaut.sample@contoso.com",
  "PrimarySmtpAddress": "exonaut-sample-mailUsers@contoso.com"
}

Notes: Doc-derived from Wiki + write-param allowlist; not live-captured. Body fields are Wiki-valid; values are illustrative.

Related: GET /exchange/v1.0/mailUsers

DELETE /exchange/v1.0/mailUsers/{key}

DELETE /mailUsers/{key} - destructive. Use ?permanentlyDelete=true to skip the recoverable-items window.

Backing cmdlet: Remove-MailUser. Role: Recipient.ReadWrite (Pro).

Parameter	In	Type	Required	Description
`permanentlyDelete`	query	bool (switch)
`dryRun`	query	bool (switch)

Delete a mail user

Removes a mail-enabled user via Remove-MailUser. Use ?permanentlyDelete=true to skip the recoverable-items window. Returns 204 No Content.

DELETE /exchange/v1.0/mailUsers/{key} HTTP/1.1
Authorization: Bearer {token}
Content-Type: application/json

HTTP/1.1 204 No Content

Notes: Doc-derived from Wiki + write-param allowlist; not live-captured. Body fields are Wiki-valid; values are illustrative.

Related: GET /exchange/v1.0/mailUsers

?dryRun=true previews of any write stay on Community.