You need to see the source code of the emails that are being sent. Most likely the hackers have got your contact list in some way but it is probable that they are not using your email account to send the emails. It is possible to fake in your email address as the sender.
My reaction to this, unless you have your email on letterheads and business cards, would be to open a new email account, advise all my contacts of the new email address, and put in an auto forwarder from your old to the new address. Every time a wanted email arrives on your old address I would then advise/remind the sender of you new address. After 6 months I would then cancel the old address and advise all your contacts to blacklist the old address.
Sage advice. This is similar to advice I got from BT. Once they have your contact list, you can fiddle wth your password as much as you like but it won’t stop the spams. The horse has already bolted!
