So you gotta brand new portfolio website :). You probably already sent out an e-mail to your contacts about it. You should also add your site's url to your email signature.

Offering general advice on signatures is easy, sure. But anyone who has tried to implement automatic signatures in Outlook, Gmail or Yahoo knows it’s not always that simple. Here are some resources to help you get yours right every time and end your emails with a flair.

Outlook
How to Add E-mail signature on Microsoft Outlook 

Gmail
Adding a signature to Gmail

Hotmail
How to Make an Email Signature for Hotmail

Yahoo
How do I add or change a signature in Yahoo Mail?

Apple Mail
Mac OS X Mail: How to add a signature to your email

iPhone
iPhone 101: Updating your "Sent from my iPhone" email signature

BlackBerry
How to Add a Signature to Emails on BlackBerry Curve

Palm Pre 
Palm Pre: Add Email Signature

Entourage
Setting up E-mail signature on Entourage

Thunderbirb
How to Create a Signature in Thunderbird Email

 

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Futher reading/Resources:

The Art And Science Of The Email Signature
The 4 Personalities of Poor Email Signatures
20 Tips for Creating an Effective Email SignatureAbout the Signature Block on Wikipedia
Email Signature Etiquette