Unable to add shared MS Exchange mailbox to Apple Mail

Be aware that on October 1st Microsoft disabled basic authentication for Exchange. This results in an inability to log in to Exchange accounts and for your email client to constantly ask for your password.

You can read about it here, but generally if you have a recent system (iOS, MacOS) it can be resolved by deleting the account on your device and recreating it. It will then default to using the required authentication method.

This may not be your issue but the timeline is about right and the symptoms align.

Also Chart with Apple support was not successful. Only recommendation to delete the exchange account and set up again (70.000 emails.....)

Nevertheless that is the way to do it.

The "Account/username cannot be verified" is uselessly vague and merely indicates an inability for the Exchange server to communicate with Mail. The only way to fix it is to follow the instructions for Remove your email account, then add it back in If you can’t send or receive email on your Mac - Apple Support.

Otherwise it's a problem with the Exchange server configuration over which you probably have no control.

Thanks for this answer and it works to an extent, but since MFA is enforced, it requires authentication which doesn't really work with shared accounts.

Have you found a way around this?

Are you the administrator of said mailbox? If no, you could ask the system administrator to reset your username and password for you and then log back in again on the exchange server.

When I was a system admin back in the days, that helped for some users

Thank you very much for your help...

Indeed it is not in exchange but in office365 users

> choose the shared email

> click on ...

> click on reset password

> uncheck create automatic password

> put a password "Strong or more 

> check send me the information by email

click on " Reset password " > click on " Send me information by e-mail

switch to mail

> add an Exchange account and hop... (login of the shared email + the special password).

Et voilà...

Thanks Hlohner

Rergads

Guillaume

Hi Hlohner, although I am an administrator on the domain name, I have not found how to assign a password to the user associated (other than the user's login/pass) to the shared mailbox.