Fix host not reachable error for office 365 mailbox


  • Used Zammad version: 4.2
  • Used Zammad installation type: package
  • Operating system: Centos 7.8
  • Browser + version: Chrome latest

Expected behavior:

  • Able to config office 365 IMAP inbound

Actual behavior:

  • got Host not reachable error

Steps to reproduce the behavior:

  • Go to Email channel and configure one office 365 inbound, will get the error message.

My office 365 IMAP inboud has been working well with Zammad since last year. After a scheduled password reset at outlook side, I need to update the password at Zammad as well. However, the simple password update task took me 10+ hours.

After hours of troubleshooting, we found actually it is office 365 side blocked the basic authentication (IMAP and POP3). Though it was working well before the password reset.

The solution is to setup MFA by following the guide

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