Sometimes this type of error message is accurate, sometimes it isn't. Aside from the error message, do you know for a fact that the emails in question did NOT go through? Maybe your friends mailbox has a storage limit? Maybe friend's ISP thinks your email is SPAM? There are probably several possibilities. These are just the first ones I could think of.

Thanks azinoh for your reply. Yes, I know for a fact that the mails did not go through and yes she has checked her storage and she has deleted my name and address from her account and then re-entered it (somebody suggested that). I would say that 6 out of 10 emaiils go through but then 4 (not in a row, just occasionally) do not. Since some of my emails go through and some randomly do not, it doesn't seem like a spam situation. We are stymied.

Oh and just for the record, this has happened before and just as 'out of the blue' as it started happening, it stopped all by itself.

Anytime I hace gotten mailer daemon messages they would tell me exactly why it was returned like mailbox full and stuff. Is there more in the error message thar might give a clue? Mary

Thanks, dadoes! We both surely do feel that it is well beyond our control :)

Mary (crafty) the only message is "Unable to deliver message after multiple retries, giving up."

I'm giving up also!

You'll get a "I can't deliver" message if the receiver's mail box is full (The mail box on his server). Check the email-box size limit at yours and his ISP (Internet service provider).

Emails reside at one of two places: at the ISP or the user's computer. When an email is sent, it is stored in a file space at the ISP. It can be read and left there or it can be downloaded to the recipient's computer. Once downloaded to the recipient's computer, it is removed from the ISP.

If the recipient has been reading mail on his ISP and leaving it there, it will eventually pile up until it reaches the file size limit allowed for his account. At that point, no more email can be received until some old emails are removed.

"JemDandy: Once downloaded to the recipient's computer, it is removed from the ISP."

Not necessarily. Removal/deletion from the ISP's server depends on the configuration of the e-mail client program (MS Outlook, Thunderbird, etc., whatever may be involved). They all have an option to leave a copy of downloaded mail on the server, typically with a user-selectable choice of retention period. Configured in IMAP mode, ALL mail is always left on the server until it's manually deleted (from ALL server-side folder, including the Deleted Items holding folder), or dragged out of server-side folders to local folders.

Failure to deliver for a filled-up recipient mailbox usually bounces immediately on one attempt.

Thank you for that idea, Jemdandy, but it wasn't a full mail box, that was one of the first things we thought of.

The issue has disappeared and (if it runs true to form) won't come back for a few months but will probably happen again one of these days.

Happy New Year!

Edited to remove comment.