Hacking Gmail

Part I — Starting to Use Gmail
Moving on from the keyboard shortcuts, the next section shows you how you can
avoid them altogether by using filters.
Plus Addressing and Filtering
One little-known feature of the more old school e-mail systems is the one called
plus addressing. It can be exceptionally useful both in Gmail and in your other
e-mail systems, and I use it extensively for things such as mailing lists and weblog
commenting.
In a nutshell, Gmail ignores anything in the first half of an e-mail address after a
plus sign. So 
[e-mail]
is treated
in exactly the same way as 
[e-mail]
. It is not, as you might
expect, a different address. You can put anything after the plus sign except for a
space or an at (@) sign, and it always gets delivered to your real Inbox. Figure 3-5
should prove that it works.