Originally Posted by Mennojd
I did get a workable workaround from 1 of my colleagues though. Change the number of days to synchronize from (default) 3 to All (everything).
From the mail client go to settings/send and receive/download past mail and select All. Now e-mails are synchronizing fine again
Working here so far but it's not been long... Anyone know this workaround to fail in the end?