Random duplicated emails

[Gerald Galster]

> 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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