@JagWaugh Ooh, that’s a problem! 
Good thing you noticed that before flipping the switch. The experimental mbox importer does a really nice job with setting the expected dates from the emails sent so luckily we didn’t have that kind of problem.
Thanks for the tip about the category watches! It does look like imported accounts aren’t watching the defaults, probably because we didn’t think to set them before the import. Oops.