mail account "stealing"

Let's say you have a mail account blabla[[[ at ]]]gmail.com or hotmail.com, doesn't really matter!

One day you see you have received a message by blabla[[[ at ]]]gmail.com, which is you!
Other friends might also get a message by you, which you haven't sent, but sender is blabla[[[ at ]]]gmail.com.

How does this practice work and is it any way to stop it?

PS: I have to make clear I am NOT infected by any worm of any kind! I know only that it is some kind of bot, that is able to "cheat" on sender information.

edit://I found this topic -> Can Someone Steal Your Email to Send Spam?

This seems to be my case:

Omg this SO sucks!

 

A few days ago I found a site for sending anonymous email, where you could specify a sender. So I could send an email and it would appear that its from blabla [at] gmail.com or any other address.

I think this might be the trick used...

 

Hello,
It's called masquerading. I've done it myself when setting up a sendmail server. Nothing special. Just means you shouldn't pay attention to email header - but the content.
Mrk

 

Thanx guys!

It surely fools a lot of people. Today I got a mail from a girlfriend filled with advertisments to Viagra like products

 

Maybe it really was from a girlfriend and she was trying to tell you something

 

Hey PiCo, maybe it was your girlfriend, lol.

 

hahaahhahaha