Mailer daemon from one of my yahoo email address, message sending failure?

As far as I know, you'll only receive that whenever your message fails to send. It might be that you misspelled the email address of the receiver or the email address of the person you're sending to is already inactive.

Hi friend, may be some one used your account and send mails from it or it is just a spam message. Be careful and change your password to avoid unwanted access.

This is quite a common thing. It DOESN'T mean that your account has been hacked or that someone else has used your account! It is relatively easy to change the From: field and the Reply to: field in an email. When you (and most people) send an email, the software will automatically put your own email address in those fields but spammers, in particular, want to hide their real email address, so they use a special software which can fill in those fields with false addresses. Usually they will use a random address from their list of addresses (I have even occasionally received emails which were apparently from me!) and this is what has happened in your case. Clearly, some of the addresses that this spammer sent the email to did'nt exist and so the email clients sent a 'bounce' message to the address listed in the From: field. Unfortunately, there is not a lot you can do about it. Your email address is out there somewhere on some spammer's list and there's no way that you can remove it or have it removed. How it got there is a long story - there are many possibilities and it's now too late to worry about. About the worst thing you can do, however, is to reply to a spammer or respond to their message. That will automatically tell them that your address is valid and you will only get more spam. It's important to understand what these bounce messages are and not to be concerned about them. Just deleting them when you see them is all that you need to do.

Friend according to my opinion this message is received when you sending mail if failed due to wrong e-mail ID, Id is not exist or server problem. I also received this type of mail more time. So I think you not worry about it. No one is using your account but you should change password and password should be strong. In yahoo you received mailer daemon and in rediff a message is appeared that bounce your mail. If mail is not going.

grrr my yahoo mail did this to me... I have sent several emails and they were answered already. but now they are coming at me after a few days and it has mailer daemon message.. I can't understand for they had been sent as message. after a short while it was not even sent. grrrr