Setting the sync window (number of days back to sync)
The ActiveSync protocol has a notion of a sync window, which is the number of days back of email to fetch from the server.
By default Speaking Email will set this to One Day Back initially. Whenever there are fewer than 100 emails Speaking Email will automatically extend the sync window. You can set the window yourself and turn off the automatic growing feature.
Go into Preferences > Account Specific Settings > You account
If you are on Office 365 you will also see the Mail Protocol switch which enables you to change to Office 365 Direct. We recommend changing to this if it's available and works with your account type. It does use a number of days back sync window, but will instead download all your latest emails (up to the maximum set in preferences, usually 250).