Issue Some mail accounts appear to be lost and are fixed with a repair

[mr-wolf]

Yesterday I was called by a client who couldn't receive mail.
The mail got bounced because the user did not exist.
I did a "plesk repair mail <domain>" and it was immediately fixed.

Today I got another call and again it was solved the same way....

swaks -f info@provider.com -t info@client.nl -s 127.0.0.1
=== Trying 127.0.0.1:25...
=== Connected to 127.0.0.1.
<-  220 ns4.provider.com ESMTP Postfix (Ubuntu)
 -> EHLO ns4.provider.com
<-  250-ns4.provider.com
<-  250-PIPELINING
<-  250-SIZE 35840000
<-  250-ETRN
<-  250-STARTTLS
<-  250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN
<-  250-XFORWARD NAME ADDR PROTO HELO SOURCE PORT IDENT
<-  250-ENHANCEDSTATUSCODES
<-  250-8BITMIME
<-  250 DSN
 -> MAIL FROM:<info@provider.com>
<-  250 2.1.0 Ok
 -> RCPT TO:<info@client.nl>
<** 550 5.1.1 <info@client.nl>: Recipient address rejected: User unknown in virtual mailbox table
 -> QUIT
<-  221 2.0.0 Bye
=== Connection closed with remote host.
root@ns4:~# plesk repair mail client.nl

Repairing the mail server configuration
    Reconfiguring the settings of domains: client.nl ......... [OK]
    Reconfiguring the mailboxes ..................................... [OK]

Error messages: 0; Warnings: 0; Errors resolved: 0

root@ns4:~# swaks -f info@provider.com -t info@client.nl -s 127.0.0.1
=== Trying 127.0.0.1:25...
=== Connected to 127.0.0.1.
<-  220 ns4.provider.com ESMTP Postfix (Ubuntu)
 -> EHLO ns4.provider.com
<-  250-ns4.provider.com
<-  250-PIPELINING
<-  250-SIZE 35840000
<-  250-ETRN
<-  250-STARTTLS
<-  250-AUTH DIGEST-MD5 CRAM-MD5 PLAIN LOGIN
<-  250-XFORWARD NAME ADDR PROTO HELO SOURCE PORT IDENT
<-  250-ENHANCEDSTATUSCODES
<-  250-8BITMIME
<-  250 DSN
 -> MAIL FROM:<info@provider.com>
<-  250 2.1.0 Ok
 -> RCPT TO:<info@client.nl>
<-  250 2.1.5 Ok
 -> DATA
<-  354 End data with <CR><LF>.<CR><LF>
 -> Date: Tue, 30 May 2017 17:08:15 +0200
 -> To: info@client.nl
 -> From: info@provider.com
 -> Subject: test Tue, 30 May 2017 17:08:15 +0200
 -> X-Mailer: swaks v20130209.0 jetmore.org/john/code/swaks/
 ->
 -> This is a test mailing
 ->
 -> .
<-  250 2.0.0 Ok: queued as 7DA763532708
 -> QUIT
<-  221 2.0.0 Bye
=== Connection closed with remote host.

Because this was the 2nd time I had this problem I let it reconfigure all the domains.

plesk repair mail

How is this possible?
This happened overnight. None of these addresses had problems before.

Do note that no errors were found, yet the problem was resolved

Error messages: 0; Warnings: 0; Errors resolved: 0

The other accounts of the domain that had this problem yesterday were still working at the time.

 

[mr-wolf]

I did some digging in the maillog and the first occurence is on May 23rd at 17:10 and it's only mail to alias addresses, although not all.
The ones that kept working after that moment never failed.
The ones that started failing never stopped failing until the plesk repair was done.

The file /var/spool/postfix/plesk/aliases.db has date May 30th 17:09 , but that file was probably created when I ran "plesk repair mail"

What could have happened between May 23rd 17:03 and 17:10 ????