Hi
I don't see any reason that an System Image file wouldn't backup your email as long as it's all on drive C\:
It basically just copies the whole dive, boot sector and all, and when you restore it, it restores the drive, or partition back to exactly the way it was when you backed it up.
I've kind of ignored the incremental aspect, and just make a new System Image every few weeks, or immediately after making any major change.
With my new SSD it only takes 12 to 15 minutes to make the backup.
I always keep the last three in case something gets corrupted and goes wrong.
I've had that happen with Acronis when I needed it most, but that was a long time ago.
I only backup my C:\ drive and none of my software, games or data is on it...