I believe that I have finally resolved the problem on my MacBook when starting Mail.app that it would display this error message “SyncServer has unexpectedly quit” with a relaunch button.
After doing a few google searches I found a site that referenced this problem a way to resolve it.
Link
Since, I wasn’t using .Mac for anything the solution was to:
1) Delete the following folder: /Users//Library/Application Support/SyncServices/
2) Reboot
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