I eagerly installed the IMF into my production Exchange environment on the day it was released and unfortunately tripped over my own eagerness. I have 2 servers in a front/back-end setup and I applied SP1 to my front-end and installed IMF there and everything was okay and both installs went smoothly. My backend Server because I had clients connecting to it I wanted to wait until I could schedule an outage to apply SP1 so I didn't upgrade this straight away. Since the IMF installed okay and I couldn't find anything that told me I needed SP1 on all my Exchange servers I decided to turned it on and test it out. Well it worked "sort of" the SCL was being set fine on all the messages going though and my Back-End server was responding to this but instead of just junking all mail with the default SCL of 8 it was junking every email. Going back over all the doco I couldn't see any problems with my install so I put it down to not having SP1 on my Back-end Server. Last night I managed to get SP1 on my Back-End Server and this morning re-enabled the IMF and everything is now fine. The anti-spam Infrastructure has been around since the release of 2003 so I still find it a little weird that I had this problem but so far I like the IMF.
As well as EWS and Remote PowerShell (RPS) other mail protocols POP3, IMAP and SMTP have had OAuth authentication enabled in Exchange Online (Official announcement here ). A while ago I created this script that used Opportunistic TLS to perform a Telnet style test against a SMTP server using SMTP AUTH. Now that oAuth authentication has been enabled in office365 I've updated this script to be able to use oAuth instead of SMTP Auth to test against Office365. I've also included a function to actually send a Message. Token Acquisition To Send a Mail using oAuth you first need to get an Access token from Azure AD there are plenty of ways of doing this in PowerShell. You could use a library like MSAL or ADAL (just google your favoured method) or use a library less approach which I've included with this script . Whatever way you do this you need to make sure that your application registration https://docs.microsoft.com/en-us/azure/active-directory/develop/quickstart-register-