Mochten bovenstaande oplossingen niet helpen is deze oplossing door Microsoft zelf aangegeven:
1.Go in Exchange Admin Center-->mail flow-->rules-->create a new rule.
2.In this new rule, introduce any name you want, then click on the "More options." button.
3.Go to the "Apply this rule if-->"A message header"-->"includes any of these words" then after you selected all of these, click on the "Enter text" and introduce " Return-Path". For the "Enter words", type the following "bounces@maxicms.nl" then click on the + button, then click OK.
4.Go to the "Do the following"-->"Modify the message properties"-->"set the spam confidence level(SCL)-->"Bypass spam filtering" then click on the save button."