I keep getting "mail delivery system failure" emails and I haven't sent emails to the addresses indicated. I've tried changing my password, to no avail. Please help!

When people receive emails which appear to come from their own address but they haven't sent (or bounces of messages that appear to come from their address) they naturally tend to be concerned: however it's most unlikely that anyone has hacked their account, they've just been targeted by one of two common spammers' techniques: both arise because it's all too easy to forge the 'from' address on messages to be something other than the real one.

There are two things that can happen. One is that the sender has forged the 'from' address to be the same as the 'to' address (so other people will see it coming from themselves, not you), presumably in the hope of confusing spam filters. It's harmless, if extremely annoying. Delete it (never ever answer spam or try to unsubscribe from it), and you don't need to be worried about it.

The other problem, which is apparently the one affecting you, is that a spammer is forging your address as the 'from' address on a whole batch of messages. The first thing you hear about this is when you start getting bounce messages because the spam has been sent to non-existent addresses and is being bounced to you. There's no point at all in responding to it. It's infuriating but normally stops after a bit as they move on to another forged address.

As its unlikely to be a case of your account being hacked and used to send the messages there isn't really anything you can do about it: closing the account isn't really worth the hassle unless you are totally swamped, because you will have to tell everyone your new address. Apple can't really do any more than they already are about spam.

If you really want to abandon the present iCloud account just sign out of it on all your devices and forget about it: you can't delete it from the server, but it will just collect email until it's full and then bounce them with an 'account over limit' error.

If this is the same thing my wife had, I found a fix. Mail would return that we did not send and would copy itself every deletion. I had 3 of these. select all of the emails at one i.e. highlight them all. Drag them into a created or other trash folder than the account you found it in. All the emails should now be in that trash folder. Simply delete.

This worked for me. Good Luck.

I had this problem. This seems to have worked:

Select All

Go to More>

From should be filled out by something like MAILER-DAEMON@whatevercompany.com

Choose> Create Filter

Then choose Delete as Filter

That should eradicate spam

margier1

What email 'account' is receiving these 'fail to deliver' messages? i.e., @me, @icloud, @gMail, YahooMail - @ymail or @yahoo? Your ISP provided?

CCC

Most of the time, that indicates that someone hacked into, stole, and/or bought your email address (or got it from someone else who had your address) and is using your legitimate email address to send out spam emails to many people; some of those email addresses may not be in use, so you (as the supposed "sender" since it's your address) are getting the notification that it couldn't be delivered.

Changing the password is a great idea; however, they already have your email address. The only sure way to stop this is to abandon that account and establish a new one with a very difficult to guess password. Usually, those notifications will slow down/stop; if they do not, consider dropping this account (which is a drastic measure, but sometimes the only solution). Other than that, not much you can do. FWIW, it is irrelevant which account is getting these - it can happen to any account; although a web based account may be a tad easier to hack into.

As its unlikely to be a case of your account being hacked and used to send the messages

Unfortunately, that happens to Yahoo accounts regularly.

I'd suspect that the OP has found an answer since they have not been active here for 2 years.