I wonder if a Shared Mailbox, which from what I understand obviously needs an Azure Account, but no Exchange License (at least when I'm fine with a few limitations) is enough in order to use it as SMTP gateway for third-party applications. We come form Exchange on-prem where an AD user didn't necessarily was required to have an Exchange Mail-Box, ms-Exch-SMTP-Accept-Authoritative-Domain-Sender permission on a certain SMTP Connector was enough.
Therefore we have several applications which need to use SMTP, internally and world-wide. This post https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/how-to-set-up-a-multifunction-device-or-application-to-send-email-using-microsoft-365-or-office-365 does not really sas clear what the minimum requirement for an AzureAD/Exchange user is in order to use it for third-party SMTP.
From what I figured, a shared mailbox + send as permissions on certain mailboxes/distribution lists in charge, seems to work for me. But is this the right approach to go, at least if I do not want to receive Emails on such addresses?
And also, in the on-prem world we didn't have to deal a lot with the From Address, any Address was accepted and emails got delivered, at least internally. Is it required to have a mailbox or distribution list + send as for each and any from address I'd like to use? Thinking of printers or other devices, there is no need for a reply on those notification emails....
thanks in advance,