Thanks @ahazelwood. I know it really depends on the use case. My core point is: Considering both scenarios and using them at the maximum capacity allowed. If I move all...

Ok, Thanks a lot Jo Pattyn. I do also think that everything will continue to work after new year´s eve.

Let´s wait and see.

Well, actually I´m not sure if we use Exchange Online or not... In the account configuration we do use a local smtp-server, but at the end this local server connects...