Google

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 [...]

Below is typical phishing email I received on Dec 8, 2007. It was send to one of my active gmail accounts.

The Email Header

From

“Gmail Team” <customercareteamalert4@gmail.com>

Subject

Gmail Warning!!!! Verify Your Gmail Account To Avoid Close.

Part of the message ↓

Dear member,

This message is from gmail message center to all gmail free account owners
and premium account owners. We are currently upgrading our data base and
e-mail account center. We are deleting all unused gmail account to create
more space for new accounts.

*To prevent your account from closing, you will have to verify it below so
that we will know that it’s a present used account.*

* CONFIRM YOUR IDENTITY. VERIFY YOUR FREE GMAIL ACCOUNT NOW !!! [...]

IMG ALT attribute is one of favorites places for spamming keywords. (Blackhat SEO).

As this has been a trend lately so Matt Cutts (Google Head of Webspam Team) provide a general guide on applying “proper” ALT attributes inside image tags. Check out the video →.