Incoming email that's blocked usually means that defenses are in place and are working. That's a "good thing" in most cases.

If you find messages in your Sent Mail box that you didn't send, you should suspect a very big problem<sup>1

1</sup> - unless you have a cat that likes to walk around on your keyboard and you tend to leave programs open while the computer is unattended. This could produce a single unintended sent message. Malware usually will send many.

Cat(s) - yes.
Unattended at our house - NEVER! (because of the multiple cats).

John