Duplicate article when replying to ticket

[Zammadammaz]

Infos:

• Used Zammad version: 5.0.x
• Used Zammad installation type: (source, package, docker-compose, …) docker-compose
• Operating system: Ubuntu 20.04 LTS
• Browser + version: Chrome and Firefox

Expected behavior:

• Reply to a customer-generated ticket and see only a single response article.

Actual behavior:

• Since upgrading from 3.1.x to 5.0.x we’re seeing duplicate articles when agent replies to ticket. Looking at the raw headers they are exactly the same except except two extra lines in the duplicate article raw file – it has a RETURN-PATH: and RECEIVED:
  I’ve looked through the aliases, groups, and triggers and they’re the same as before the upgrade. The support inbox is support@ourdomain.com and the alias is set up as the same.

Steps to reproduce the behavior:

• Customer sends email to the monitored (IMAP) mailbox, Zammad picks it up and creates a ticket for it. Agent then hits the REPLY icon and enter text, hit’s bottom-right UPDATE button.
  
  

[Zammadammaz]

As an added comment. When watching the Gmail inbox, when I reply to a ticket I also see an email in the support Gmail inbox. It’s as if Zammad is BCC’ing the support inbox since it has the correct customer email in the TO:

I checked the Rails container for the system_bcc settings but it’s currently “”. Anyone know why replies to customers are also sending to our monitored Gmail support inbox?

[MrGeneration]

If I would have to guess:
You’re replying to an address that loops back to Zammad.

This is the only -to me known- situation were above behavior would appear.
Especially because on agent side the sender seems to differ.

The only way to tell better would to have a one by one compare and ensuring that affected email addresses to not cause any looping.