What is Legacy Sync Mode

Legacy Sync mode is a sync setting in MailCal that forces MailCal to use a legacy method for syncing emails with Exchange Server. This solution is useful for those users who observe that emails are not syncing. The root cause for this issue is that user's Exchange Server doesn't support, or doesn't properly response to "Change Subscriptions" sync method that is the default/primary sync method in MailCal. 

Symptoms of Sync Issues

Legacy Sync setting is a potential solution if you are observing the following anomalies: 

  • Initial setup of the account completes successfully and you see emails that were fetched during the initial setup
  • However, after the initial setup, subsequent sync (automatic or manual) do not fetch additional emails and calendar entries (or modifications)

How to Enable Legacy Sync

Go to Settings -> Account -> Troubleshoot Account,  and use the option labeled as 'Legacy Sync' to enable it. Please see screenshot below highlighting this option: 

What will be difference in App Functionality after enabling Legacy Sync

Once you enable legacy sync, the app will perform automatic background sync only for INBOX and CALENDAR. The remaining folders will still appear in the app, but will only be synced "when you open those folders" or if you try to manually sync them. This is done to preserve battery life as unlike the newer Sync Method, Legacy Sync has to scan for changes on each sync cycle. In a future update, a setting will be added to allow you to select additional folders for automatic sync when running in Legacy Sync mode.