Specific e-mail did not trigger a ticket creation

Infos:

  • Used Zammad version: zammad/unknown 3.6.0-1613047982.332fdca8.xenial amd64 [upgradable from: 3.6.0-1611733683.51a3d218.xenial]
  • Installation method (source, package, …): package
  • Operating system: ubuntu 16.04
  • Database + version: psql (PostgreSQL) 9.5.24
  • Elasticsearch version: 5.6.16
  • Browser + version: -

Expected behavior:

Recieved email will create a ticket

Actual behavior:

it didn’t, but only in one speicific case (as far as i know)

Steps to reproduce the behavior:

After some searching, I’m pretty sure this is a bug, but I need your help to find the actual information you need.

I use the IMAP connector, every mail that is recieved on that mailbox will create a ticket, this worked fine for over 4000 tickets now. Today I got a call from a customer, who asked if he recieved the mail, because he didn’t get any reply.
I checked in zammad, no ticket there. So I checked the mailserver log, maybe the mail got denied, but no, it was accepted.
So I went into the mailbox of the imap account I use for zammad, to check if the mail was declared as spam, but that wasn’t also the case, its right there in the inbox between all the other mails, that did trigger a ticket creation.
So I checked production.log.1 (as it was yesterday), but nothing with ERROR or WARN in that timerange, so I searched for the customers e-mail-address, and parts of it. No success either. This is where I am completely lost.
I can’t explain myself why this happened, except it’s a bug.

Just a guess, but if someone is reading in the mailkbox Zammad reads in, that one might mark a mail as read before Zammad could have a look at that mail. If that happens, Zammad will not fetch the mail in question.

Marking the mail as unread and wait for the fetch would be a theoretical workaround to double tab.
Zammad will mark the mail as read after.

If the mail does still not appear, you may want to have a look within /opt/zammad/tmp/unprocessible_mail.