Issue Abnormal traffic usage caused by POP3/IMAP

[stevepa]

Server operating system version

Ubuntu 20.04.6 LTS

Plesk version and microupdate number

18.0.63 Update #4

Dear all,

I've got asubscription for a customer in my plesk environment with "normal" usage of 2 GB.
Traffic was constantly 2-5GB a month, but a few months ago monthly traffic was suddenly 300, 400, 500 GB a month, up to 3 TB.

Nothing changed, costumer is still using his email as before.
All traffic is caused by POP3/IMAP. Outgoing Mail Control is enabled (max. 30 mails an hour).

There are no anomalies in /var/log/maillog and maillog.processed - this is all minimal.

Any ideas?

Thanks a lot.

 

[Sebahat.hadzhi]

Since mail accounts authentication is performed via POP3/IMAP, this may be the cause of high traffic statistics. However, you would have probably noticed lots of entries in the maillog. Could you please try one of the following scripts and let us know what's the result you see?

 

[ChristophRo]

maybe a stuck email in the inbox, that the client tries to download over and over again? (I've only seen such things in the past, when using POP3)

 

[stevepa]

maybe a stuck email in the inbox, that the client tries to download over and over again? (I've only seen such things in the past, when using POP3)

yes it seems so, but how to find out which client is causing this issue? any ideas?

 

[stevepa]

Since mail accounts authentication is performed via POP3/IMAP, this may be the cause of high traffic statistics. However, you would have probably noticed lots of entries in the maillog. Could you please try one of the following scripts and let us know what's the result you see?

POP3/IMAP stats for info@********.net

Bytes:
SENT=340539725191
RCVD=8086097

KiloBytes:
SENT=332558325.38
RCVD=7896.58

MegaBytes:
SENT=324763.99
RCVD=7.71

GigaBytes:
SENT=317.15
RCVD=.01