They are a dignified, classy, subtle way to promote your organization. A few words of caution. Successful marketing is not selling. We get enough of that in the mail and via endless calls from telemarketers. Successful marketing is about developing relationships by establishing helpful, consistent contact.
Repetition is critical.
The more times you reach your current and potential customers with information they value, the more credibility and familiarity you build. Then, when the customer is ready to buy, you will be remembered. Get to the essence of your message in the first paragraph. Tell them how your firm can solve their problems in a cost-effective way. Learn how to punctuate and abbreviate, and be consistent in every issue.