Hi Ronald,
Perhaps the following page will help you with the issues: https://support.office.com/nl-nl/article/Een-multifunctioneel-apparaat-of-een-toepassing-instellen-voor-het-verzenden-van-e-mail-via-Office-365-69f58e99-c550-4274-ad18-c805d654b4c4?ui=nl-NL&rs=nl-NL&ad=NL#option2.
This could be a Office 365 configuration issue.
Good luck.