Somebody using my email for spam?

I keep getting failure delivery's to one of my website emails, I never really thought much to it and just deleted them. However I got about 50 of them today so I decided to check it out. The failed emails are the sort of spam I get (eg pictures of words offering me viagra and such). The thing is, I haven't sent those emails. They are showing as being sent from (oxam@mydomain.com showed up alot), thing is, I haven't registered those email adresses.

So my question is, is this happening because of a security flaw, a setting in my host email account I haven't set up right or is it just one of those things I have to accept happens?

 

never happened to me before, but all infos on this one are important to all of us.
someone?

 

No, there most likely isn't a security flaw. View the email's headers and check the IP from which the mails originate.

 

i also get such mails in my hotmail account its all crap inside

 

Someone is using your domain to spam. Unfortunately, there is almost nothing to do except to report the sender to its IPS, using abuse@isp.

Cheers !
Thibaut