A new office, like a new home, is often a source of pride and a call for celebration. Sending a congratulatory letter is a gracious gesture and shows that you take an interest in your customers.
1234, Main Street
Boston, MA 02123
<Recipient Address Goes Here>
Congratulations on your new <describe the new office space>. <Compliment new office.>
<Refer to success.> We wish you continued success at your new location.
encl: <List of enclosed items goes here>