Pfff….finally. It was something that was long overdue, but I’ve setup my mailserver to allow sending mail after succesfully logging in. Done with SASL of course. Updated all the passwords in my MySQL database with the correct encrypted ones, fiddled around with the SASL-database (it needs to be copied for some reason after modifying it), and now it works. The reason of course was to use the switchbl8.nl domain for sending mail from my mobile phone (which is not on my local network, so by default isn’t allow to relay mail to other domains).
Most important change is also that my passwords are not send plain/unencrypted anymore…