hi, it could be a virus, or it could be that someone has gained access to your password.
I would change your password as step 1 and see if the problem goes away.
Go to www.verizon.com/repair and click change password
Then I would probably run a virus scan.
Do you own a virus scanner?
Verizon offers the mcafee virus protection, but if you never signed up for it, they have a 3 time use-free version. www.verizon.com/freetools
Run a scan using that.
additionally run a scan using both of these free spyware softwares
There are also free virus scanners online too, so you can try those if you want to be EXTRA sure that you are protected.
The same thing happened to me on the 16th. I just discovered it this morning. I use outlook on my computer to manage all my email. I found all of the outbound messages in the online mail service but not in outlook. Looks like someone accessed my online contact lists(outdated by 4 years). I looked at my computer logs and it looks like there were some strange entries about computer access without success. Looks like online access was somehow compromised. I changed my mail password and the password to my computer. Quick scan did not show any virus. Full scan still running.