You can have up to 6 additional email accounts in Comcast besides your primary account. Sign on to your primary account and click on the Users & Settings tab at the top of the page. You should see a link in blue underneath your user name that says Create Secondary User.
If you notice yellow leaves in other areas of the tomato plant, or the yellowing at the bottom is spreading upward, this could be a sign of disease, such as curly top virus (usually curly top virus will show signs of yellowing leaves that are curling up as well), Ringtop Virus, or other diseases.
Bacterial spots and blight are two of the most common issues that can cause brown spots on a tomato plant's leaves. Particular details of the brown spot can help you identify the cause of the spotting so you can determine how to stop it from spreading.