I've read the last days multiple documentations and tutorials, but didn't find the answer for my question, although it is in my opinion an obviously elementary question.

We use two servers and three Office365 email addresses (report@<companyname>.de, service@<companyname>.de & support@<companyname>.de). Both servers use a PhpMailer to send emails from theses email addresses via SMTP. One server additionally fetches the emails from these three addresses via IMAP in the same intra net php program, where the PhphMailer is located.

Because Basic Auth is deprecated, i have to switch to Oauth (for Microsoft Oauth 2.0). Therefor i need to know, how many registrations are necessary for my usecase.

I think at least two - one for each server. But is one (for each server) for all our @<companyname>.de email adresses enough?

CodePudding user response：

You wouldn't need to register each one separately (unless you really want to), they could use the same app registration in your O365 tenant if you want - they can connect using the same client credentials. You're registering an application as the client, not a physical server. You can have many different programs all using the same O365 app registration credentials if you want to. There are good and bad points to doing that, you just have to decide how to organise it yourself.

If all the email addresses you're trying to interact with are in the same O365 tenant you should only need 1 app registration, the app just needs the appropriate permissions in the Graph API.