MobileMe: Email messages not received by a recipient

Resolution

These tips should help to resolve the issue:

• If an "Unknown address" or "Undelivered mail returned" message appeared in your inbox after you sent the message, verify that the recipient's email address is current and the correct address (look in your Sent messages mailbox).
• If you are using Mail (in Mac OS X) or Webmail (in Safari or a different Web browser), verify that the mail has been sent. Check your Drafts, Sent, and Outbox mailboxes. If there is an unsent copy of the message in Drafts, try to send it again.
• If you receive a message such as "This message could not be delivered and will remain in your Outbox until it can be delivered..." when trying to send this (or any other) email, see this article.
• Ask the recipient to check any "Junk" mail folders or mailboxes on their end. Perhaps your message was received but inadvertently filtered.
• If your recipient still does not receive your mail but your mail is being sent without any alerts or "Undelivered mail" messages, then your mail might be blocked or filtered by the mail systems at .MobileMe or the recipient's location. The best way to determine if this is the issue is to contact MobileMe Support directly and have your recipient contact his or her email administrator to find out if there is a known block in place.