EXO Mail Enabled Users are not showing as mail enabled in on-prem Exchange

Question

Hi,

We have few ids created in on-prem Active Directory using New-ADUser command and updated the mail attributes to get them as mail enabled users in EXO. However, these ids are not showing as mail enabled users in on-prem Exchange.

If we try to update them as mail enabled users in on-prem Exchange getting error as below

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This task does not support recipients of this type. The specified recipient KPLDOM.COM/India/Amruta N is of type
MailUser. Please make sure that this recipient matches the required recipient type for this task.

• CategoryInfo : InvalidArgument: (ADDOM.COM/India/username:ADObjectId) [Enable-MailUser], RecipientTask
  Exception

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Appreciate any support in resolving this.

Regards
Mahesh

Answer 1

If you have on-prem Exchange, then enable the existing AD accounts as remote mailboxes, not with enable-mailuser

https://learn.microsoft.com/en-us/powershell/module/exchange/enable-remotemailbox?view=exchange-ps

Enable-RemoteMailbox "Kim Akers" -RemoteRoutingAddress "******@contoso.mail.onmicrosoft.com"

Answer 2

Hi,

Thanks for the response. Appreciate your help.

Tried with the command but no luck, this is already showing as RemoteMailbox

----------------------------------------------------------------------------------------

This task does not support recipients of this type. The specified recipient
DmainDOM.COM/India/"Username" is of type RemoteUserMailbox.

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My worry is

1. Why this is not shown as Mail User in On-prem Exchange?
2. Will there be any impact if it doesn't show in on-prem Exchange?
3. If i want to compare with other user who is showing as Mail User in on-prem Exchange, what should be the parameter/attribute we need look for identifying the difference?

Thanks, and Regards
Mahesh

Answer 3

Hi Team,

Thanks for the details...here are the details

1. Mail Enabled user in EXO are not shown as Contact in on-prem Exchange if they are created with switch as Enable-RemoteMailbox. Infact, EXO Mailbox and EXO Mail User is same in On-prem Exchange, this can be seen in on-prem Exchange Admin Center.
2. If User is created as Mail-Enabled through Exchange PowerShell or Admin Center, then only it shows as Mail User in on-prem Exchange.

In Both cases, all Mailbox and Mail users will be available in GAL and mail can be delivered to destination .

Regards
Mahesh