A mail bomb virus is a denial of service attack, whereby a large and excessive (often millions) amount of e-mails are sent to an account often preventing retrieval of legitimate mail.
The three best ways to avoid this virus is to – make sure to download and apply any security patches available to your e- mail. Check your virus scanner has built in e-mail scanning. Apply a setting to your e-mails which most providers offer so e-mail can only be read in plain text format.