If you send email in the United Kingdom take note. In an effort to fight spam, the U.K. recently put new laws into effect that require companies to disclose sender information in their transactional and other commercial email messages.
Extending a law covering traditional business communications to include email, the UK Companies Act Amendments of 2006, which took effect January 1, require companies incorporated in Great Britain and overseas companies that operate in Great Britain to disclose the company name, where the company is registered, the registration number (if applicable) and registered address in their transactional emails. The amendments also require senders of non-transactional commercial messages, such as marketing messages or e-newsletters, to include the company name and a valid physical postal address in each message.
The new rules could prove challenging for the significant percentage of British companies still struggling to comply with the 2003 E.U. Directive on Privacy and Electronic Communications. While there is some ambiguity regarding exactly what's covered by the new regulations, the Email Sender and Provider Coalition is counseling in favor of including the required information for all email-based marketing and transactional material. You can read more in this BizReport article, and in this ESPC member briefing (PDF).