A fairly low-tech solution to this problem is http://iammoving.com/ which allows you to automate the notification of lots of companies. This site is pretty useless, in my opinion, because none of the companies that I want to update are on the list. The process is also error-prone.

I'm proposing a more high-tech solution, a Trust Server, that will soon become as ubiquitous as Email Servers.

Each Trust Server is run by a company with a good reputation for security, a company that you trust to hold all your personal details. I'm sure that Verisign would consider themselves such a company? I'm not so sure...

Each Trust Server provides a web interface for you to add and maintain all your contact details. When your circumstances change, you go to the web interface and update your details.

Instead of giving companies your address details, you would give them a unique identifier (your email address?) that would allow them to work out which Trust Server you hold your details on. This lookup process would work in a similar way to how an SMTP server works out which email server to send a message to, given an email address.

Each company would communicate with the Trust Server using a digitally signed XML format message. By signing the messages, the Trust Server knows who is asking for details.

When a new company sends a message to the Trust Server, you get an email asking you to log onto the Trust Server via the web interface and decide whether to allow access to your contact details. Crucially, you decide *which* contact details each company has access to. You may want some companies to know your mobile phone number. Others, you might want to restrict to only your mailing addres.

The Trust Server would help companies in the UK comply with the Data Protection Act. Each user controls how much information each company has access to and can remove access at any time. If companies don't cache contact details in a database of their own, they don't really have any Data Protection issues to worry about.

Your friends could also use the information in your Trust Server rather than holding your contact details directly. This would mean that their information is never out of date.