Endorsement letter marketing is having a client or supplier recommend your product or service to others. Typically they agree to mail a letter (you write it, they approve it) to their client list talking about how you helped them solve a problem and maybe it makes some sense for them to talk to you.
Before asking anyone for an endorsement be sure they are happy with your product or service.
Once you find the ideal client or supplier to endorse your product or service, call and invite them out to lunch. Ask them face-to-face if they will do an endorcement mailing for you.
When proposing an endorsement deal make sure there is something in it for the person endorsing you. That by endowsing you, it ultimatly helps their client.
If they're selling a product or service, you could exchange endorsements. Last year a collegue of mine and I did a mutual mailing for each other. We each mailed to 100 of our clients, prospects and suppliers recommeding each other services. He landed three new clients I landed one. That one brought in over $10,000 in business.
Sometimes you'll be ask to pay a fee, try to give them a percentage of the profits or a finders fee of any new clients landed instead. Pay for performance.
Endorsement letter marketing can increase your sales fast. It gives credibility to your product or service. As you know people will usually believe a person that's not related to your business before they will believe you.