Failure to deliver email notifications

[condor]

Over the last few weeks I've been getting numerous failure to deliver email notifications that someone else is sending using my main email address. How concerned should I be that my email account is being used and how can I prevent it ?
The email header says the culprit is
know_smtprelay-11-imp
though the number 11 has also been 10 and 9, it's just 11 appears more often than the other numbers.

Anyone able to advise please?
Thanks

[condor]

Sorry but I don't understand the acronyms you're using. I delete the returned email notifications as soon as I get them- and they don't appear in my trash folder, whereas proper emails I've deleted are still there. It's my own personal email account that I've had from Virgin media since NTL days. The title notifier is
[e-mail]
It then reads failure to send email to ( various different email addresses)

[condor]

Thanks for your help - it's of some comfort that it's not too bad to be overly worried about

Here's one I received earlier - I have never clicked the 'original message' attachment as I suspect it would be a virus of some sort.

This is the mail system at host know-smtprelay-10-imp.

I am sorry to have to inform you that your message, "Fwd: Fw: to Theresa Hopkins", could not be delivered to [e-mail].

The remote mail system said;
550:5.1.1 <[e-mail]>: Recipient address rejected: aol.com

The original message is attached.

[condor]

I don't have my own domain, this is my personal email account.
Should I report it to Virgin media, who has been my ISP for many years?

[condor]

I have a business gmail account and a hotmail account for any sites that want me to sign up that I'm not overly interested in.
My Virgin media account is used for private 'friend and family' type emails.

[condor]

One month later and still getting a load of these mail deliverer notifications - the max has been 22 in a short time frame (ie 2 mins in a day) I've had to delete.

Not sure if this is a coincidence or not , but my Amazon password has been reset by someone using my email account to reset it. I've had email notifications to ask me to reply with a number and then another to say it's been reset - which I have sent to their 'stop-spoofing@Amazon' account. Had an automated reply to say it's been passed to security to investigate.

Fortunately, I don't keep my credit card details held on my Amazon account. A sensible precaution to take nowadays.

[condor]

An update in case this will help anyone else.
My local area lost internet access for 2 days last week -I think now is a good time to ring retentions team and see what deals they can give me. I cite the fact there's currently no internet, and have all these spam emails. I'm passed to technical support who say they'll fix it.
Yesterday, I couldn't gain access to my email account as 'someone' had changed the password. I ring tech support again and my email account has been blocked due to the sending of spam messages.
All sorted for the time being now, but I'd advise it's a good idea to ring your ISP's technical support team as they can help if it's not your fault.