If you put in your email address book
aaa@aa.com or something to that effect any worm or virus that tries to get into you email account to spread their worst will stop with you as a virus etc is spread via the address book..if the first address it gets is confusing to it then it stops dead in its tracks.
Got this from an internet magazine 3 years ago and if everyone did this then virus's and worms that spread via email would become obsolete.