Problem Sending AOL Messages

With long time history of successfully sending mail to multiple addresses in groups, we recently began getting returned mail from AOL users in the groups. No AOL user in a group is getting mail, but they previously did. The message:

This is anautomatically generated Delivery Status Notification. THIS IS A WARNING MESSAGE ONLY. YOU DO NOT NEED TO RESEND YOUR MESSAGE. Delivery to the following recipients has been delayed.

The second message:

Your message did not reach some or all of the intended recipients.

Subject:
Sent:

The folowing recipient(s) could not be reached:

xx@aol.com on 3/14/2003 11:01 AM
Could not deliver the message in the time limit specified. Please retry or contact your adminsitrator.