Office 365 and HP Printers.
We have a suite of MFPs for printing and scanning. Up until recently, our LEA provided us with a free SMTP service for scanning to email. That's now been withdrawn because of spamming issues. Unfortunately, if we can't use Office365 as an SMTP alternative, because it requires TLS authentication, which is not supported on HP printers. I've gone through setting up an outward facing server as an SMTP relay, which satisifes the printers when testing the validity of the listed SMTP server, but the mail doesn't get through to the recipient.