sieve on the new mail server
If you don't know what "sieve on the new mail server" is, you can safely ignore this message. Incorrect permissions on sieve scripts caused sieve filters to be ignored from at least 16:21 April 13 (or perhaps earlier - we got no complaints and it's hard to tell) until the problem was fixed at 13:47 April 14. Mail would have been delivered directly to your INBOX, and a vacation message (if done via sieve) would have been ignored. If you are on the new mail server and use sieve, please check your INBOX for mail that was not filtered properly.

