User ID vs user e-mail (local vs oauth)

[kimjas]

When people in the organization mail in to Zammad, a user account with their email address is created. When they then (in some cases) later go to log in with Microsoft, using that mail address, they get denied because the email address is already used.

Should it really be impossble to have more than one user id with the same email address? The Microsoft accounts get a long SID from Microsoft as their user ID anyway. This seems like a doubtful design choice. Especially as I’ve found no other way to rectify this except to GDPR-delete the automatically created user created by the incoming e-mail and thus deleting cases out of the system as well.

Is there any way to deal with this situation that doesn’t lead to erasing information?

Running Zammad 6.41 on Ubuntu 24LTS - fairly recently installed. Not that that is relevant for the issue.

[MrGeneration]

If you would have read the actual error message, you’d know that Zammad complaints about the email address already being known to Zammad. It has nothing to do with Microsofts SIDs etc. This applies to all third party authentications.

You have to explicitly enable automatic account linking.
See our documentation for more input: Third-Party Applications — Zammad Admin Documentation documentation