If you connect your mobile device using ActiveSync, only current appointments and e-mails will by synchronized. This is a function of the design and concept of ActiveSync and is not related to our services. Normally, past e-mails are only synced by ActiveSync for a few days.
With mailbox.org, you can currently sync your e-mails from the last 18 months.
In addition, we have determined that the service does not always interact properly with some mobile devices and versions. If you would like to sync past e-mails, enter a time period of up to ‘1 month’ in your mobile device. Longer periods of time can cause problems in some mobile devices.
Use the CardDAV, CalDAV, and IMAP protocols to sync all of your data.