At 1911Z we upgraded a component of our system that caused emails sent through Office365 and possibly other email providers to be delayed. This change was reverted at 2200Z and email should now be delivered without issues. Some users may have to resync their accounts to clear any remaining errors. The issue appears to be caused by an incompatibility between encryption capabilities but we are continuing to research the failures to identity the exact cause. We're sorry for any inconvenience this may have caused.