[Larry]

You can also add "+text" after an email address like:

[email protected]

This will also go to [email protected]

This is useful (including using various versions with ".") to track how your email address is being shared. If you use say "+dell" for interactions will Dell (for example) you'll see if Dell shares your email address with any other company.

 

[Larry]

Here is the info on this from google:

http://mail.google.com/support/inproduct/bin/answer.py?hl=en&answer=12096

In terms of filtering.... the only problem would be if your email client will not allow you to send a message to an email address with a "+". Incoming, gmail servers redirect the email to you real address, but you can still see the original address as composed.