To showcase the service the alarm company Sector Alarm provides, we installed an alarm in an envelope that went off when the letter is opened (the alarm rang for 8 seconds). It helped us grab recipient's attention, and helped make our sales reps cold calls a little warmer.

Each letter was sent out with a handwritten address and signed in person by a sales rep. The selection of potential clients was based on a list that the sales reps themselves had created. Two days after the letter was sent out, the sales rep called or visited with the client they had sent the letter to. The campaign ran with a total of 1000 letters sent.

Sales reps reported whopping 100 % of recipients that opened the letter remembered it when the sales reps contacted them. The sale increased with 28 %.