Forum Discussion
Zakon
Jan 26, 2023Copper Contributor
Exchange hybrid - on-premise mailbox issue
Hi Guys,
I have a problem with mailbox that is located in on-premise Exchange 2019. I'm using hybrid mode with 99% mailboxes located in EXO. Let's name this mailbox: "Mailbox1".
Mailbox1 have 4 SMTP addresses. 3 of them are working correctly, only 1 is not working- mails sent on this SMTP are not delivered with error:
: 550 5.1.10 RESOLVER.ADR.RecipientNotFound; Recipient XXXXXXXXX not found by SMTP address lookup
While I'm sending mail from this specific SMTP mail is delivered correctly - reply on this message is also not delivered.
I have found some discussions that could be related to this issue. For example:
All my accepted domains in EXO are configured as Authoritative. But I'm not sure that this is the root cause of this issue because it's working with 3 others SMTP for same mailbox and also some other mailboxes from on-premise are working correctly(some- not, same issue as described).
Do you have any experience with issue similar to this one?
BR,
Zakon
- Deleted
The bounce back is returned when the recipient address isn't available on the server where your MX is pointing to.
Please confirm if the 4 SMTP addresses on Mailbox 1 are of the same domain name.
Please confirm if there are other working mailboxes (Mailbox 2, mailbox 3) with address like the affected domain name on Mailbox 1
I look forward to your response in order to advise further.
- ZakonCopper Contributor@update
There are 2 objects in cloud:
1. MailUser without required SMTP address added
2. MsolUser with all SMTP synced from on-premise
I'm not sure why on-premise mailbox is synced to MsolUser instead of MailUser.
Both ExchangeGuid for on-premise Mailbox and MailUser are same.
Any ideas?- Dan_SnapeSteel ContributorNot sure that you have this correct. MSOLUser is the user in AAD (found using get-MsolUser cmdlet). The mail user should be the same user but found in Exchange Online using the get-mailuser cmdlet. If you have TWO users found in AAD (and possibly EXO) with the same details, then you have a problem. Check the AAD Connect health to see if there are any sync errors. You might see an indication of duplicate addresses or user type mismatches
- J_TsaiCopper ContributorDo you see the SMTP address listed for the MailUser object in EOL? Run in EOL==> (Get-MailUser Mailbox1).EmailAddresses
The address you're using have the correct email type "smtp:"?- ZakonCopper ContributorSMTP addresses that were added into mailbox(on-premise) are sycned to MsolUser object instead of MailUser object in cloud. Any ideas how to fix that issue without excluding object from sync and deleting both objects in cloud?