I might be able to provide more detailed information, if I knew which kind of account it was. Hotmail? Gmail? No matter which one, it's imperative you can change your password. The below I copied from a prior post (of mine), where a member's Windows Live account was compromised. The information is universal. The settings may vary, according to the account.
''When your account has been compromised, the most important things you can do, is change your password, and change your secret question and answer, . Have you done that?
If you're unable to access your account to re-set your password, see if Account Password Recovery, offers any additional information.
Important Security Information To Know,
Recent reports of Account hijacks, " ''
You might also try scanning with Malwarebytes' Anti-Malware and/or SUPERAntiSpyware. Both are free. Malwarebyte's Anti-Malware can be downloaded from here or (directly) from here. And SUPERAntiSpyware FREE Edition from here.
Best of luck..
I am running IE9 on Windows 7 Professional and have Kaspersky 2011 anti-virus on my computer. Within the last day or so, my email address is being used to send out emails for Viagra etc. A number of "undeliverable mail" starting popping up. I ran the Kaspersky and nothing shows up! Ran a full scan and ran a critical areas scan and nothing!! What do I do?