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- Server operating system version
- Ubuntu 22.04
- Plesk version and microupdate number
- 18.0.74 Update #3
I am having an issue where sometimes email sent to a forward only email address on the server does not get correctly forwarded to the target
Additionally I am confused by what I see in the log files although I will admit I am not overly familiar with how the email forwarding flow is supposed to work
The scanario:-
Plesk is installed hosting mydomain.co.uk
Plesk Version
Plesk Obsidian Web Host Edition
Version 18.0.74 Update #3
Server Software
Ubuntu 22.04
Configuration
I have multiple email forward accounts set up. All are configured the same
Do not allow login to plex with the email
Mailbox size 0
Switch On mail forwarding is selected
Do not copy to inbox is selected
Two of the email recipient forwarding configs that created the most recent problem (there have been other undelivered test mails)
mydomain_user1@mydomain.co.uk -> gmail_user1@gmail.com
mydomain_user2@mydomain.co.uk -> outlook_user2@outlook.com
Two days ago I created both addresses and sent a single email with mydomain_user1@mydomain.co.uk and mydomain_user2@mydomain.co.uk as recipients
mydomain_user2 received the email correctly. Mydomain_user1 one did not and today I received a bounce back saying mailbox full
The testmail came from my gmail account
mydomain_admin@gmail.com
However trawling through the log chain things do not make sense to me
Here's an excerpt from the logfile
What confuses me greatly is that from the logs it appears that mydomain_user1@mydomain.co.uk was passed to gmail instaed of gmail_user1@gmail.com
The processing of the second recipient of the email is as follows:-
While this mail was delivered successfully I'm confused by the last chronological entry in the excerpt which seems to imply that the email was redirected to outlook with a sender who is completely unknown. It has munged together my email mydomain_admin@gmail.com with the domain name mydomain.co.uk to produce a fictitious mydomain_admin@mydomain.co.uk as the sender.
However outlook_user2@outlook replied to that message and it arrived back at mydomain_admin@gmail.com so perhaps the mail log format is just incorrectly configured (I have changed nothing) or I am misunderstanding the log file
To further cement that mis-config/understanding option I today sent another message to mydomain_user1@mydomain.co.uk only which was succesfully delivered with the correct reply to address
The log started with
1266A403A5: from=<mydomain_admin@gmail.com>, to=<mydomain_user1@mydomain.co.uk>, dirname=/var/qmail/mailnames
and ended with
7133141DCD: to=<gmail_user1@gmail.com>, relay=n1smtpout.europe.secureserver.net[92.204.64.1]:25, delay=0.07, delays=0.01/0.01/0.01/0.04, dsn=2.0.0, status=sent (250 2.0.0 awpQvcwYax89x mail accepted for delivery)
Along the way was the created non-existent user. This is the same from report as the previous correctly delivered email
7133141DCD: uid=30 from=<SRS0=Abbk=7F=gmail.com=mydomain_admin@mydomain.co.uk>
This seemed to follow a completely different path being sent to a relay
It seems like I'm up against 2 issues
1) Either the logging is misconfigured or I am misunderstanding it because as far as I can see the From: user reported in the logs does not exist
2) Sometimes mail simply isn't delivered.
From the logs (which may or may not be correctly reporting events and/or may or may not be understood correctly) it appears that it was presented to the final destination with completely incorrect credentials. Could it be that two recipients both of which are forwards/aliases has confused the system.
Am I misunderstanding configuration and the mailbox full message is from my server despite being configured not to add emails to the inbox. And if that's the case why did the mail to mydomain_user2 complete with the same config. As well as the repeated mail to mydomain_user1 which also successfully completed
I'm thoroughly bamboozled but as always when a hardware engineer messes with software there a suspicion of PEBKAC
Regards
Spicey
Additionally I am confused by what I see in the log files although I will admit I am not overly familiar with how the email forwarding flow is supposed to work
The scanario:-
Plesk is installed hosting mydomain.co.uk
Plesk Version
Plesk Obsidian Web Host Edition
Version 18.0.74 Update #3
Server Software
Ubuntu 22.04
Configuration
I have multiple email forward accounts set up. All are configured the same
Do not allow login to plex with the email
Mailbox size 0
Switch On mail forwarding is selected
Do not copy to inbox is selected
Two of the email recipient forwarding configs that created the most recent problem (there have been other undelivered test mails)
mydomain_user1@mydomain.co.uk -> gmail_user1@gmail.com
mydomain_user2@mydomain.co.uk -> outlook_user2@outlook.com
Two days ago I created both addresses and sent a single email with mydomain_user1@mydomain.co.uk and mydomain_user2@mydomain.co.uk as recipients
mydomain_user2 received the email correctly. Mydomain_user1 one did not and today I received a bounce back saying mailbox full
The testmail came from my gmail account
mydomain_admin@gmail.com
However trawling through the log chain things do not make sense to me
Here's an excerpt from the logfile
| 2025-12-29 14:37:10 | info | postfix/smtpd [862674] | 12A01416D4: client=mail-pf1-f169.google.com[209.85.210.169] |
| 2025-12-29 14:37:10 | info | postfix/cleanup [862677] | 0C229416D4: milter-reject: END-OF-MESSAGE from mail-pf1-f181.google.com[209.85.210.181]: 4.2.2 Mailbox full; from=<mydomain_admin@gmail.com> to=<mydomain_user1@mydomain.co.uk> proto=ESMTP helo=<mail-pf1-f181.google.com> |
| 2025-12-29 14:37:10 | info | psa-pc-remote [1141] | 0C229416D4: check-quota: stderr: DEFER |
| 2025-12-29 14:37:10 | info | psa-pc-remote [1141] | 0C229416D4: check-quota: stderr: DATA REPLY:452:4.2.2 Mailbox full |
| 2025-12-29 14:37:10 | info | postfix/cleanup [862677] | 0C229416D4: message-id=<CABjuiC87W+Lfa97fkz0YRe90DBQ_xPn-D29hgU8WGtGXU3y4Cw@mail.gmail.com> |
| 2025-12-29 14:37:10 | info | psa-pc-remote [1141] | 0C229416D4: from=<mydomain_admin@gmail.com> to=<mydomain_user1@mydomain.co.uk> |
| 2025-12-29 14:37:10 | info | postfix/smtpd [862672] | 0C229416D4: client=mail-pf1-f181.google.com[209.85.210.181] |
| 2025-12-29 14:37:09 | info | postfix/smtpd [862674] | connect from mail-pf1-f169.google.com[209.85.210.169] |
| 2025-12-29 14:37:09 | info | postfix/smtpd [862672] | connect from mail-pf1-f181.google.com[209.85.210.181] |
What confuses me greatly is that from the logs it appears that mydomain_user1@mydomain.co.uk was passed to gmail instaed of gmail_user1@gmail.com
The processing of the second recipient of the email is as follows:-
| 2025-12-29 14:37:10 | info | postfix-local [862685] | 12A01416D4: send message: id=S862685 from=<SRS0=1Zyd=7D=gmail.com=mydomain_admin@mydomain.co.uk> to=<outlook_user2@outlook.com> |
| 2025-12-29 14:37:10 | info | postfix/smtpd [862672] | disconnect from mail-pf1-f181.google.com[209.85.210.181] ehlo=2 starttls=1 mail=1 rcpt=1 bdat=0/1 quit=1 commands=6/7 |
| 2025-12-29 14:37:10 | info | postfix-local [862685] | 12A01416D4: arc-sign: stderr: SKIP |
| 2025-12-29 14:37:10 | info | postfix-local [862685] | 12A01416D4: from=<mydomain_admin@gmail.com>, to=mydomain_user2@mydomain.co.uk>, dirname=/var/qmail/mailnames |
| 2025-12-29 14:37:10 | info | postfix/qmgr [4215] | 12A01416D4: from=mydomain_admin@gmail.com>, size=3570, nrcpt=1 (queue active) |
| 2025-12-29 14:37:10 | info | psa-pc-remote [1141] | 12A01416D4: check-quota: stderr: SKIP |
| 2025-12-29 14:37:10 | info | postfix/cleanup [862677] | 12A01416D4: message-id=<CABjuiC87W+Lfa97fkz0YRe90DBQ_xPn-D29hgU8WGtGXU3y4Cw@mail.gmail.com> |
| 2025-12-29 14:37:10 | info | psa-pc-remote [1141] | 12A01416D4: from=<mydomain_admin@gmail.com> to=<mydomain_user2@mydomain.co.uk> |
While this mail was delivered successfully I'm confused by the last chronological entry in the excerpt which seems to imply that the email was redirected to outlook with a sender who is completely unknown. It has munged together my email mydomain_admin@gmail.com with the domain name mydomain.co.uk to produce a fictitious mydomain_admin@mydomain.co.uk as the sender.
However outlook_user2@outlook replied to that message and it arrived back at mydomain_admin@gmail.com so perhaps the mail log format is just incorrectly configured (I have changed nothing) or I am misunderstanding the log file
To further cement that mis-config/understanding option I today sent another message to mydomain_user1@mydomain.co.uk only which was succesfully delivered with the correct reply to address
The log started with
1266A403A5: from=<mydomain_admin@gmail.com>, to=<mydomain_user1@mydomain.co.uk>, dirname=/var/qmail/mailnames
and ended with
7133141DCD: to=<gmail_user1@gmail.com>, relay=n1smtpout.europe.secureserver.net[92.204.64.1]:25, delay=0.07, delays=0.01/0.01/0.01/0.04, dsn=2.0.0, status=sent (250 2.0.0 awpQvcwYax89x mail accepted for delivery)
Along the way was the created non-existent user. This is the same from report as the previous correctly delivered email
7133141DCD: uid=30 from=<SRS0=Abbk=7F=gmail.com=mydomain_admin@mydomain.co.uk>
This seemed to follow a completely different path being sent to a relay
It seems like I'm up against 2 issues
1) Either the logging is misconfigured or I am misunderstanding it because as far as I can see the From: user reported in the logs does not exist
2) Sometimes mail simply isn't delivered.
From the logs (which may or may not be correctly reporting events and/or may or may not be understood correctly) it appears that it was presented to the final destination with completely incorrect credentials. Could it be that two recipients both of which are forwards/aliases has confused the system.
Am I misunderstanding configuration and the mailbox full message is from my server despite being configured not to add emails to the inbox. And if that's the case why did the mail to mydomain_user2 complete with the same config. As well as the repeated mail to mydomain_user1 which also successfully completed
I'm thoroughly bamboozled but as always when a hardware engineer messes with software there a suspicion of PEBKAC
Regards
Spicey
