what is mailer-daemon@.bullet-re3.yahoo.co.uk failure notice?

It means that your outgoing messege was not sent properly. Possibel to an improper e-mail address. When u see that notcie it means that your mail was NOT sent.

A mailer-daemon failure notice is usually sent either when the inbox at the email address that you're sending the email to is full or when the email address no longer exists.

I hope this helps. ♥

I`ve had that before but I don`t open it. The email I got it for was always received but I`ve seen that question on here before and some people say theirs didn`t . I always check to see if mine did.

Its an address failure notice.

well every time ive sent an email and it didnt get sent for whatever reason, i get an email from mailer-damion saying that they are sorry but they couldnt send my email.

Either the address is wrong or their mailbox is full and can't be delivered at that time.