Because e-mail is one of the chief means of transporting viruses, most antivirus programs have options that help them work with your e-mail program. This only applies when you are using a “local” e-mail program to read and send mail, and not when you are using a Web browser to handle your mail.
The options that you’ll most likely see are used to specify whether your antivirus program should scan incoming mail messages, and whether it should scan outgoing mail messages. If you see such options, you should turn them on.
Your antivirus program might install buttons in your e-mail program that permit you to scan specific messages (or all messages) in the inbox or another mail folder. There could also be a button installed on e-mail that will let you open your antivirus program right from within your e-mail program.