If it's a web based email service like gmail, yahoo etc then change the password immediately.. use a strong one with 12 characters minimum, upper and lower case, numbers and a non-alphanumeric character or two. If the address book is stored locally like Outlook or Thunderbird for eg then it would be a good idea to do some scans on the computer to make sure you haven't picked up some sort of malware/exploit.
Check the thread at the top of this forum for the recommended scans..
THANKS for the advice,
Ive changed the password.
I used to get in there with my fire fox browser, without
signing in... gues that is not a good thing,
maybe I should take the trouble to sign in each time
and dont click on fire fox... remember this password ?
I m doing a "super anti spyware" scan and 2 trojans have
come up... hopefully they will be zapped
Its prob trojans that are sending out the e mails
microsoft xp Home Edition
Service Pack 3
Intel (R) Core (TM)2 Duo CPU
E 4500 @ 2.20 GHz
3.00 GB of RAM