in the past we have been accessing several shared mailboxes by using the following method:
real.account@acme.com\shared.mailbox@acme.com
smtp.office365.com:993/tls
etc.
whilest real.account@acme.com has read / write permission on the shared.mailbox@acme.com.
With the current implementation it seems that we are still able to send messages with the sender shared.mailbox@acme.com but receiving messages does not work. We assume this is because the channel will look into the account real.account@acme.com only.
In 365, all shared mailboxes have an associated account, I normally disable it once the mailbox is ready, but for the Zammad mailboxes I set a (really good) password and log in using those. I don’t set MFA on those accounts, but with the new 365 OAuth2 access you could. You’ll need to use that soon anyway if you’re not already, as MS are shutting down basic auth on IMAP this year.
The folder path isn’t supposed to work, so it’s interesting you’ve had it working in the past.
Thank you for your feedback. Everything works fine and this without actually changing the current setup. The “trick” was @tomsparrow’ input:
After checking in the user > active user list in M365 we noticed that there is a reset password function for shared mailboxes too. Once done and set we were able to connect to the shared mailbox without any issues!