I have a strange situation where several users have shown up that have very strange email addresses and are not manageable. The users have the following email format:
name_thierdomain#EXT#@mydomain.com
The first part looks like a full email address where the @ was replaced by an _.
If i tick the checkbox for the user I get a message on the right side that I cannot edit external users and only the Delete option is available.
I have a call into MS support but though I would see if anyone knows what this is, whether I should delete them and what effect it might have?
I thought it might be someone that was invited to a meeting and had not accepted or something like that. Or maybe someone shared a file or calendar externally (which we don't allow). None of these seem like valid reasons this should be happening.
Hope I'm not hacked!