E-mail messages not delivered to external server even when local postoffice is disabled

[q-quan]

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TITLE

E-mail messages not delivered to external server even when local postoffice is disabled

PRODUCT, VERSION, OPERATING SYSTEM, ARCHITECTURE

Plesk 18.0.69, Windows Server 2025, MailEnable

PROBLEM DESCRIPTION

I have multiple domains hosted on my Plesk server. One of these has its mail service set to "Disabled", as its mail is handled externally. According to this support page, that should be enough for messages sent from another local domain using the local mail server to be sent to the external mail server, instead of being attempted to deliver locally.

However, I found that is not the case: such messages would not arrive. Only setting the mail server to "Not configured", removing the postoffice from MailEnable entirely and removing all existing mailboxes and messages (not an issue in my case, but I imagine other use cases where old mailboxes should be preserved) fixed this. I believe this should be fixed, or at least, the support page updated accordingly.

STEPS TO REPRODUCE

- Set up domain X with its mail DNS records pointing to an external e-mail server, and the local mail service for this domain "Disabled".
- Set up domain Y as default with local mail.

Send an e-mail message from domain Y to domain X.

ACTUAL RESULT

Message arrives on external mail service

EXPECTED RESULT

Message does not arrive anywhere

ANY ADDITIONAL INFORMATION

Other details to note: I use the SmartHost option to route outgoing e-mail. That may be relevant, although I don't believe it should affect this.

YOUR EXPECTATIONS FROM PLESK SERVICE TEAM

Confirm bug

 

[Sebahat.hadzhi]

Thank you for the report, @q-quan

ACTUAL RESULT

Message arrives on external mail service

EXPECTED RESULT

Message does not arrive anywhere

It sounds like the answers are swapped by mistake, but I still would like you to confirm.

 

[q-quan]

Hi Sebahat, sorry for my late reply. Indeed, the answers are swapped.

 

[Sebahat.hadzhi]

Thank you for the confirmation. I attempted to reproduce the issue, however, the server is attempting to properly deliver the email message to the remote server when mail service is disabled locally. The first entry is for local delivery the second with disabled mail service

C:\Program Files (x86)\Mail Enable\Logging\MTA>type MTA-Activity-250523.log

05/23/25 14:20:03 [732C5BA6595A4EFDA72EE5FD623020AB.MAI] from (SF) [SMTP:[email protected]]->[SF:testplesk.com/admin] Mapped Literal
05/23/25 14:33:44 [08A05D1E119044EB96991D648CCD2B65.MAI] from (SF) [SMTP:[email protected]]->[SMTP:[email protected]] System Default Route Applied.

C:\Program Files (x86)\Mail Enable\Logging\SMTP>type SMTP-Debug-250523.log
05/23/25 14:35:09 ME-I1350: [2A20BEBED7EE40E48D7F7E0A3F33312C.MAI] Attempting to connect to MX 5 of 5 (Remote MX record).
05/23/25 14:35:09 ME-IXXXX: [2A20BEBED7EE40E48D7F7E0A3F33312C.MAI] DNS resolved to the following record: IP Address= Remote server IP, Family=2, Type=1, Protocol=6

I do believe that SmartHost could be interfering on your server. Is there any way to temporarily disable it for the sake of testing? If not, what I can recommend is to check the logs in C:\Program Files (x86)\Mail Enable\Logging\ and more specifically the Debug and Activity logs under the SMTP folder.