If the email address is visible in the traffic's payload then you should be able to create a custom signature that matches the email address and block the traffic ... you'll might have to decrypt traffic though.
That said, could you please elaborate on what exactly you're trying to achieve ? Block 1 specific address/domain/email service ?
Click Accept as Solution to acknowledge that the answer to your question has been provided.
The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!
These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the LIVEcommunity as a whole!
The LIVEcommunity thanks you for your participation!