This morning I was sent a Spam Email offering me 75% discount on Viagra - nothing new about that, right? But, the SENDER WAS MY YAHOO EMAIL ADDRESS!!!

I have emailed Yahoo Support, and just awaiting a reply from them (hopefully soon).

Just wondered if anyone else has ever had this problem?
Hopefully Yahoo will deal with it, but does anybody here know - does this mean that millions of people around the world are now going to get spam from me? Or just the friends in my online address book?
Has my account been hijacked/hacked into/compramised?

I use my yahoo address for all my online/website stuff.

I don't keep personal financial records on my computer, but I am really very worried this has far-reaching consequences.
How did it happen?
I run anti-virus every day and have a firewall.
Any advice or knowledge from anyone gratefully received please!

That is quite common - anyone can send an email with any sender.....just enter a random email address in your outlook or whatever-mail programme and you can send emails from it.

In order to verify, that it is really your email address, just add a PGP key in the footer of your email.

That's scary - my yahoo address is rather unique so someone must have copied it specifically. Not like it's "maryjones@"......
Thanks for that info, but can you please tell me what a PGP key is? And how do I add it please?
And what is a PGP, how does it work/what does it do?
Thanks!

PGP = Pretty Good Privacy It’s sort of like putting a digital signature in your emails (that matches a digital signature in an email with one stored in a repository somewhere), so that recipients know the email is a genuine one from you.

Thanks Darkhorse, but I am pretty clueless as to what a Digital Signature is, or what you mean by storing one in a repository somewhere - I know what the word repository means, but just not in computer speak!
Sorry to be so clueless......any help/advice really appreciated!
I am just worried someone has hacked into some website database somewhere (how else would they have gotten my email address?).

In fact, no sooner had I posted the above than I received a spam email from a non-existent email address using one of my own domain names. Happens every day.

The email actually came from an email address @cwjamaica.com – to see the ‘headers’ for the email in Outlook, where this kind of info is, open the email, click on View, then click on Options, and a window should open and show the email headers (including the return path).

I'd say almost certainly that here really is nothing to worry about, this kind of thing happens every day to loads of people. Can't help with the digital signature I'm afraid, I've never bothered using them. Here's a link to what I assume is a fairly straight forward digital signature installation procedure - http://www.windowsitpro.com/Article/ArticleID/13695/13695.html

Like I said, I get spam from my own domains regularly (even non-existent email addresses at those domains), its just one of those things that happens......just open up a bottle of wine and forget about it

Thanks ever so much Darkhorse, you've put my mind at ease, to know its no big deal to worry about after all - I was beginning to panic and imagine all sorts of awful scenarios of hacking and me getting into trouble for being a nuisance somewhere!