Calendar on Android only syncs last two weeks
I added my Mailbox account as an Exchange account on my Google Pixel smartphone with Android 7.1.2. I can not get Calendar apps like Google Calendar or Business Calendar to sync any appointments older than two weeks. When I try to add an appointment on my phone that is older than 2 weeks, after a few seconds it disappears. I tried cleaning app cache and removing/adding the account a dozen times, but nothing works. I tried it on another Android phone as well, same problem.
It seems like there's some incompatibility between Mailbox.org and the way Android sets up Exchange accounts, because when I add my Mailbox account to a third party app that has a build in Exchange setup, all my Calendar appointments sync fine. However I would like to use Android's build in functionality with Gmail and Google Calendar, not a third party app. Is there anything I can do? Do others have this problem as well?