Many of you will already know this trick, but here it is in case anyone missed it.
Say your Gmail address is
You can put dots anywhere in the left hand part of this address, and mail will arrive just the same; so these addresses will all succeed in sending mail to your inbox:
email@example.com firstname.lastname@example.org email@example.com
… and so on.
This already lets you pull off one neat trick; if you use a different version of the same email address for family, friends, work and so on, you can later sort your inbox – manually, or via a filter – to quickly identify where each message has come from.
You can go one better, however.
If you place extra characters after the first part of your email address, separated from the original address by a +, then you’ll still get the mail arriving at your inbox. For example
will arrive at John Doe’s browser just fine.
This is great for tracking which sites are less than careful (to put it kindly) with your email address. John, being a lifetime fan of cake, wants to sign up for the newsletter at his favourite website, humungusgreatcake.com
He fills in the online registration with the email address
He’ll get the newsletters just fine. Plus, if he starts to get email spam from elsewhere sent to john.doe+hgcake, he’ll know exactly which site released his email details; he can block any future mail sent to that version of his address, then go out to wreak terrifying, cake-fuelled vengeance on those who wronged him. Or maybe just unsubscribe.