Ask most people these days what SPAM is and it'll be commonly accepted that it's grown to become a nuisance of the 21st century. Phishing and other privacy hijacking make opening your inbox more like opening Pandora's box.

The internet has grown in tandem with it's specifications, guidelines of protocol but, in my opinion, email has been less fortunate.

In an attempt to quell the increasing tide of SPAM Yahoo and Cisco implememented "DomainKeys" and "Indentified Internet Mail" respectively which later merged to become DomainKeys Identified Mail (DKIM), an IETF standards-track signature-based mechanism for authenticating email messages.

It wasn't until I came across Yahoo's over zealous spam-filter "SpamGuard" that I knew anything other than what DKIM stood for, but now I'm trying to write code to allow user's to send themselves legitimate email. In the instance of @yahoo domains that's proving less successful.

In an effort to embrace the philosophy :

DomainKeys Identified Mail (DKIM) lets an organization take responsibility for a message while it is in transit. The organization is a handler of the message, either as its originator or as an intermediary. Their reputation is the basis for evaluating whether to trust the message for delivery. Technically DKIM provides a method for validating a domain name identity that is associated with a message through cryptographic authentication.

- http://dkim.org/

I've set about trying to understand the additional signature headers and hashing algorithms for public/private key tokens to implement this with PHP. In summary I have established the following :

1. The first thing to do is establish private and public keys
2. You need to add a Resource Record(RR) to your DNS zone file. This is constructed with DKIM specification syntax
3. Lastly your email is 'wrapped' in DKIM hashing. Additional headers, again to specification syntax, are added.

As I figure out more I'll add it to this post.

Further Reading

• dkim.org:: DKIM SIgnatures
• dkim.org:: DKIM Overview
• Early implementation of DKIM for PHP

A colleague mentioned ESP's the other day, sounding more like she was having a physic moment she was in fact talking about Email Service Providers. Turns out on the the world of the inter-web that everything has to have a cool sounding acroynm and Email Service Providers is yet another example.

It is now deemed no longer cool to manage your own bulk emailing applications, rather, to pay an ESP a monthly fee to do it for you. In return they promise better deliverabililty and ROI.

This pontification all came about after a webinar professing the wonders of video in email. Sponsored and presented in part by Goodmail Systems, one of the fore-runners in video email. Naturally they are going to promote the idea, that's a large portion of their income stream, but the concept has huge potential. Syndicated video content to a mass audience. This year the buzz term for me is syndicated content. Content distributed through a huge network by content providers to a massive (pre-approved) audience. It's only natural that this should extend to email.

My only concern is that Email Standards have barely left the ground. Web browsers and internet standards, courtesy in part to the W3C, have seen a slow shift to convergence on a common set of goals and standards which even Microsoft are slowly adhering too !

However email is light-years behind. No one email client is the same, a major pain in the rear when trying to create those funky looking mail shots. Not only that but mail protocols are in need of an update. Spam and unsolicited mail are so prevelant these days that it seems a little late that only now are we seeing procedures and protocols being established to deal with a common nuisance of the 21st century.

DKIM is definately a step in the right direction.  Patented by Yahoo! this is an early shot at dealing with such nuisances. Blacklists and whitelists, the good and bad of domains, currently provide a database of information to bulk/spam mail filtering software that's frequently updated. Hopefully DKIM and MTA (Mail Transfer Agents) will add to this arsenal and provide the majority of us a long awaited shield from the rubbish floating around on the web.

Video in email ? We'll wait and see, but I think it will be big. Currently only supported by a limited number of email clients of which Yahoo! and AOL (owned by Yahoo! and remember they invented DKIM in the first place) are the two major ones, video in email will only be available to a limited email client base. One to watch.