Know-How Exchange : Customer Behavior

In that case you need a carefully crafted letter that assures recipients you are contacting them with the full knowledge and approval of your [former] employer. Brief letter, followed-up with personal phone calls.

If you need assistance preparing the letter, you might want to contact a professional copywriter. Be sure you have a personal website/landing page ready when you send out the letter. Be sure too that your LinkedIn profile is updated.

I agree that you should put special emphasis on this letter or mailer or whatever it is. And if it were me, And I were spending effort and attention and/or money, I would simultaneously try to develop a similar letter or marketing piece which I could use as a postcard, mailer, brochure, etc.

For example, if you get something professionally printed, the most expensive piece you print will be the first one. Each piece gets less expensive after that. It is possible, if you're getting something professionally done, to use the same background and color and graphics for all the letters, and simply change the text.

'Your' clients? While you may have the appropriate blessing, are the leads you're taking with you truly 'your' leads until they've converted to the new company? What of their loyalty to your soon to be former employer? Can your new employer both meet and exceed all previous deliverables, warranties, and expectations? If your answer to this questions is a hearty "YES!", can you prove it? I'm not picking holes in what you're setting out to accomplish, I really do wish you the best. My reason for this line of questioning is to protect your reputation and your client's feelings of getting what they need.