You can used this technique to register on sites and forum. To name a few → digg, myspace, newsvine, 9rules, blogger & msn etc.

Gravatar sign-up process took less than 5 minute to complete and they don’t burden you with filling form chores (i.e: address, newsletter subscriptions, marketing questionnaire). So we pick Gravatar Web services for this guide.

Requirements

You must have the following email.

1. Gmail or Google Aps Gmail

Gmail Plus-Addressing Features

In brief, Gmail services has undocumented plus-addressing features (+) since early 2004. The plus-addressing features is mostly used for writing self notes, email filtering and mapping (google maps).

“Gmail never announce this features (beta forever) as there is no official documentation at Gmail Help Center.” — Anon

RFC 2282 - Internet Message Format

Technically, the plus sign operator is a standard URI protocol for handling Email address including telephone and fax (+tel, +fax ). This standard is maintained by Internet Engineering Task Force (IETF Network Group) → RFC 2282 “Internet Official Protocol Standards - Internet Message Format”.

1. Gravatar Signup Process

The signup pages can be found at the following address ↓

• http://site.gravatar.com/signup

Normal Signup

2. Gravatar Sign-up with Gmail Plus-addressing Features

Gmail Forwarding

Example of valid Gmail plus-sign-address code.

3. How Does It Work?

• Below is raw header received from Gravatar for billgates+mypwned.avatar@gmail.com.

  Delivered-To: billgates@gmail.com
  Received: by 10.114.235.16 with SMTP id i16cs666570wah;
   Tue, 11 Dec 2007 02:13:40 -0800 (PST)
  Received: by 10.100.247.14 with SMTP id u14mr17188447anh.1196668020044;
   Tue, 11 Dec 2007 02:13:40 -0800 (PST)
  Received-SPF: fail (google.com: domain of support@gravatar.com does not designate 72.232.151.155 as permitted sender) client-ip=72.232.151.155;
  Received: by 10.36.223.23 with POP3 id v23mf1698886nzg;
   Tue, 11 Dec 2007 02:13:40 -0800 (PST)
  X-Gmail-Fetch-Info: billgates@gmail.com 1 smtp.gmail.com 995 billgates
  Delivered-To: billgates+mypwned.avatar@gmail.com
  Received: by 10.141.85.4 with SMTP id n4cs336075rvl;
   Tue, 11 Dec 2007 02:13:35 -0800 (PST)
  Received: by 10.151.7.4 with SMTP id k4mr2609357ybi.1197368014852;
   Tue, 11 Dec 2007 02:13:34 -0800 (PST)
  Return-Path: <support@gravatar.com>
  Received: from app1.dfw.gravatar.com (155.151.232.72.static.reverse.ltdomains.com [72.232.151.155])
   by mx.google.com with ESMTP id a13si6664003rnc.2007.12.11.02.13.34;
   Tue, 11 Dec 2007 02:13:34 -0800 (PST)
  Received-SPF: neutral (google.com: 72.232.151.155 is neither permitted nor denied by best guess record for domain of support@gravatar.com) client-ip=72.232.151.155;
  Authentication-Results: mx.google.com; spf=neutral (google.com: 72.232.151.155 is neither permitted nor denied by best guess record for domain of support@gravatar.com) smtp.mail=support@gravatar.com
  Received: from gravatar.com (localhost.localdomain [127.0.0.1])
  	by app1.dfw.gravatar.com (Postfix) with ESMTP id 50EB08F36CA5
  	for <billgates+mypwned.avatar@gmail.com>; Tue, 11 Dec 2007 10:13:34 +0000 (UTC)
  Date: Tue, 11 Dec 2007 10:13:34 +0000
  From: support@gravatar.com
  To: billgates+mypwned.avatar@gmail.com
  Message-Id: <475e62ce4f383_94b15911e666750191132@app1.dfw.gravatar.com.tmail>
  Subject: Welcome to Gravatar
  Mime-Version: 1.0
  Content-Type: text/plain; charset=utf-8
  
  Welcome to gravatar!
  
  To activate your account, simply click on the link below or paste into the url field on your favorite browser:
  
  http://site.gravatar.com/activate/666aff604f5eba8025c1
  
  When you visit the above page, you'll be able to set your password and create your first gravatar, all for free!
  
  If you have any questions about the system, feel free to contact us anytime at support@gravatar.com.
  
  Tom Werner
  Gravatar Founder
  

• When gmail received the email with the plus-addressing code it will split it up as follow
  • billgates+mypwned.avatar@gmail.com
  • login-name = billgates
  • filter-name = mypwned.avatar

  And Gmail will forward the email to the login-name@gmail.com → billgates@gmail.com.

Where to start

Make sure you can received the plus-sign-address email. Try compose new email with the plus sign to yourself.

Example:
Well, assume that your email account is : leeeroyjenkins@gmail.com
So compose new email like so:

From: leeeroyjenkins@gmail.com
Send-To: leeeroyjenkins+selftest@gmail.com
Subject: Hello world
Message-Body: Over, Over, Do u read me.

That should be all. check the related links for further read on Gmail tips and documentations.

Extra notes

There is few special characters you can play with.

1. Period . → billgates+all.your.base.belong.to.us@gmail.com
2. Hypen - → billgates+chuck-norris-fans-club@gmail.com
3. Asterisk *→ billgates+my*space@gmail.com

Related Links

• Gmail Official Discussion Group
• Jim’s tip on How to maintain “notes” in Gmail
• Official Gmail Advanced Search Parameters