Random duplicated emails

Gerald Galster
Mon, 09 Sep 2019 16:31:54 -0000

> I migrated our mail infrastructure to Dovecot on Ubuntu 18.04 some months
ago. It works fine, but recently some users told me that they sometime receive
duplicated emails. Same email content, same headers including message-id.
>
> I'm using two dovecot servers on two sites. Both server are in cluster.
We don't use shared folders. All users that reported this issue so far are
using the same server instance. The problematic  emails are coming from local
users on that instance too. The examples they given to me was emails with many
recipients (To/CC). A specific message can be received twice (or more) by
recipient A but only once by recipient B. I didn't see anything in the logs
about sieve rules that redirect emails to others recipients.
>
> Where should I look to diagnostic this issue?
>
> Thanks.
>
> Server config:
> # 2.2.33.2 (d6601f4ec): /etc/dovecot/dovecot.conf
> # Pigeonhole version 0.4.21 (92477967)


may be you hit this problem:

https://dovecot.org/list/dovecot/2018-March/111422.html
<https://dovecot.org/list/dovecot/2018-March/111422.html>

I don't know if it's fixed yet.

You could log mail events and check if it's related to dsync:

mail_plugins = ... mail_log

plugin {
  mail_log_events = delete undelete expunge copy mailbox_delete mailbox_rename
  mail_log_fields = uid box msgid size subject
}

Best regards,
Gerald

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