do you have a plan on unifying this with test_imap_mutation.js?  Diffing the two, except for the bits where ActiveSync lacks the awesome fidelity of repliedTo/Forwarded/Junk marking, it seems like the other changes could be accounted for with a ternary comparison as to whether the account is IMAP or not.  And I think the ternary ops could be somewhat informative to someone reading the unit tests in helping them understand the differences between IMAP and ActiveSync.

(And for those flag differences, we could 'if' those out or just put the special IMAP flags in their own test, although I think just conditionalizing them could be better.  We change change the subscripting order if needed, too.)

Specifically, I'm concerned about the tests being a hassle to keep in-sync and potentially diverging in such a way that we lose out on coverage.