Although this isn’t a common practice from the office or in the business world, sometimes business owners or service providers will send out a congratulation letter to a customer. Sending out a congratulation letter to customer needs to be short, precise and to the point, so you don’t come off as a stalker. This should be related to a non-work related matter and preferably something that doesn’t have to do with their personal life either.
This isn’t an excuse to sell anything so don’t use it as an excuse to sell anything either.
Signify the event they’re being congratulated for.
Tell them how pleased or impressed you are with them.
I would like to congratulate you as I read in the paper; your little league took the championship gold. It’s great to see a local team from around here and a special congratulation to Rich Jr. as well. You’re a very dedicated coach out there on the field and you are one of the best inspirations I’ve seen on the field.