An interesting article by Evan Schuman on his “Storefrontbacktalk” site describes how Wal-Mart’s highly secretive testing of SMS marketing in Dec-07 highlighted two important lessons:

• SMS messages are supposed to be punchy: don’t try and cram too much in
• Our mobile phones are also very personal: don’t abuse this by sending too many messages. 

One Wal-Mart employee was quoted as saying:

“We were sending 10-15 (offers) in about three or four text messages. We learned that three messages is where the consumer says, ‘I’ve heard enough from you, Mr. Retailer,’.”

Two interesting points:

1. The sheer scale of the “test”. Wal-Mart, never one to do things by half, signed up hundreds of thousands of people to the program
2. This was in the US, surely yet another sign that the States is opening up to the opportunities for business messaging.