GMail does not understand dots...

I recently discovered some little-known ways to use a GMail address that can give you greater control over your inbox and save you some time. Actually, when you choose a Gmail address, you actually get more than just "yourusername@gmail.com"; here are two different ways you can modify your Gmail address and still continue getting your mails:

• Append a plus ("+") sign and any combination of words or numbers after your email address. For example, if your name was yourusername@gmail.com, you could send mail to yourusername+friends@gmail.com or yourusername+mailinglists@gmail.com.
• Insert one or several dots (".") anywhere in your email address. Gmail doesn't recognize periods as characters in addresses -- Google mail just ignores them. For example, you could tell people your address was hikingfan@gmail.com, hiking.fan@gmail.com or hi.kin.g.fan@gmail.com.
  

For me, the real value in being able to manipulate your email address is that it makes it really easy to filter on those variants. For example you could use yourusername+bank@gmail.com when you sign up for online banking and then set up a filter to automatically star, archive or label emails addressed to yourusername+bank. You can also use this when you register for a service and think they might share your information. For example, I added "+yahoogrp" when I subscribed to some yahoo groups once, and now when I see emails from other groups to that address, I know how they got it and can apply a filter to auto-delete the mails.