Email account hacked - but Why ?!

Is there anyone out there who could explain something for me , please ? On Saturday I discovered 49 mailer daemon failure notices in my inbox. I contacted BT Yahoo and we spent a morning changing my password (several times), resetting the security question, doing a complete virus etc scan on my pc and then my account was supposed to be blocked for 24hrs so I couldn't send any emails. I was rather upset, Sunday morning, to discover another 5 failure messages awaiting me. So again, another morning spent on discussions with the sub continent. Again we went through the same procedures ... and hoorah, this morning , no failure notices when I logged on... but I shall still worry tomorrow morning as the messages were all sent between midnight and 2am UK time.
My question is this. Why would anyone want to use my email address to send emails to different non addresses so that they came back as failed ? What is the person getting by doing this ? Should I be even more alarmed please ?
I have spoken with my bank, credit cards etc but is there anything else I should do ?
Thank you.
hiljil

[Neil]

I wouldn't worry about it too much. Yes, change your password and make sure not major has been affected, but this sort of thing happens all the time, it is just spammers using peoples email accounts to send these stupid emails to your contacts in the hope someone will click on one of their dodgy links.

It will have all been done by clever computer programmes they have set up, which literally just target as many email address as possible.

Neil

Not to worry hiljil, this kind of thing happens quite a bit.

To have the failure notification in your inbox does mean something was trying to send from your outbox. Have you looked in there to see if there is a nasty spyware message hiding trying to resend itself?

People do this fishing for information, also to find functional email addresses, that kind of info can be compiled and sold on... some people

There are two route causes I would check; your computer.. could be a virus hopped inbound on another email and was missed by the antivirus.. it happens unfortunately. Take a look in the sent items and the outbox to see if you can find the originating email. If it isn't there then I would say check the webmail varient of your email account.. although BT/Yahoo should have done this already. The culprit could be hiding in there..

Fingers crossed

[preiffer]

OR someone's spoofed your address - so it never even went from your account in the first place...

[Pete]

As Reiffer says. it's most likely a spoofed send address, so your account never went near it, nor has your email be compromised. You get the return notifications because the spammer 'says' it came from you, when in reality it didn't. Sadly spoofing email addresses is easy just because of the way the system works.

Thank you all.
I was puzzled because it didn't seem that my contacts had been affected ( thank goodness) but now that you've explained about
spoofing it makes sense.
Basically, then, it doesn't matter how often I change my password as the spoofer hasn't got into My account ( fingers crossed ) .
A huge thank you.

[preiffer]

Bingo.

And sadly, every time you put your email address into a form online - you increase the chances of being spoofed. It's an unavoidable hazard of online life, and as long as there are people in the world who will click "OK" to the Nigerian Money Scam emails, they'll continue to do it...

This is one reason why I maintain a number of email addresses. When I first use a new service that asks for my email I use one of a set of quarantined addresses, and only change to my trusted address later on. Nor is that address a forename.surname format. Won't stop them but might slow them down by a microsecond or two...

Could you explain a bit more about using a quarantine email address please?

Could you explain a bit more about using a quarantine email address please?

I perhaps oversold the concept, but it's just a bunch of Gmail accounts that I only ever access over the web.