Many members of the U-M community have their @umich.edu mail forwarded to their mailboxes outside the University. From time to time, various ISPs block mail coming from the University of Michigan.
Reported June 26, 2008: mail delivery to over 30 @yahoo.com addresses fails.
Yahoo. An e-mail message sent to more than 30 @yahoo.com addresses will fail to reach any of the @yahoo.com recipients.
[This issue with Yahoo is still occurring.]
If you send a message that has more than 30 @yahoo.com recipients -- this includes mail forwarding, members of mail groups, and mail sent directly to @yahoo.com addresses -- the mail will get rejected. The rejection message will have "452 Too many recipients" for all recipients after the 30th one and the whole message will fail with "554 Transaction failed: empty DATA not allowed" error.
We have contacted Yahoo and hope they will fix this problem.
Please be aware of these minor limitations on mail forwarding:
gmail. Google's gmail generally accepts mail forwarded to its users from @umich.edu addresses. However, there can be problems when attempting to transfer an entire IMAP mailbox to gmail if the mailbox is very large. We recommend that you transfer the messages in batches of less than 2,000 to avoid problems.