Office 365 - POP3 - Mailbox not connecting in Zammad 4.0


  • Used Zammad version: ==> Setting up zammad (4.0.0-1617868443.a1cbb3a0.focal)
  • Used Zammad installation source: (source, package, …) Package
  • Operating system: Ubuntu 20.04
  • Browser + version: Chrome (latest)

Expected behavior:

Being able to continue after klicking on “Weiter”,

Actual behavior:

Getting a Red-Failure-Box stating:
“* OK The Microsoft Exchange IMAP4 service is ready. [RgBSADAAUA[…]NAA==]”

Steps to reproduce the behavior:

  • Setup an POP3 Only Mailbox on Office 365.
  • Connect via Host:
  • Username = eMail-Adress
  • Password = valid one
  • SEelect POP3 instead of IMAP
  • SSLTStartTLS = yes
  • Port: 993

According to

The POP3 - Port is 995

But changing the value of IMAP/POP3 does not switch this Port correctly, instead 993 is set any way.
It would be better not to setup the Port then.

The Modal-Dialog asks for the SMTP-Service. The Hostname of POP3 is set.

Changing this to and setting Port to 587 leads to the “Verifizieren senden und empfangen” - Information.

This fails after a few minutes with the message:
“Verification Mail not found in Mailbox”
"Unable to verify sending and receiving. Please check you settings.

By the way:
SMTP-Sending through the mailbox (instead of MTA) does work though. So generaly this function seems to work.

Zammad expects to be able to fetch the mail from the folder you specified (if applicable).
If it can’t find the mail it’s most probably because it’s looking in the wrong folder.

Besides, you may want to use the Microsoft 365 channel instead because Microsoft is shutting down Basic authentication for email accounts step by step.
See Accounts — Zammad documentation

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