Opt-in messages are sent immediately after a customer subscribes to your list, and are required by the CTIA and wireless carriers. This message includes things that can't be removed, such as stop & help instructions, information about message & data rates, and the quantity of messages a new subscriber can expect from your list. That being said, you're able to customize the top portion of the message by following the instructions below. This message is not to be used for any special offers or promotions, as that should be done in a scheduled message to new subscribers.
Instructions
Select the list you wish to create a single opt-in for by clicking the Manage button from your list of list on the dashboard.
Click the Settings icon in the list navigation bar in the top right hand corner of your list homescreen. Then select Mobile Op-tin
Confirm that "Single Opt-In" has been selected.
Enter your desired keyword in the field below "Keyword".
In the field for "Opt-In Message", enter a message to subscribers, which they'll receive immediately when they opt-in. This is usually something along the lines of "Welcome to our mobile club." This is not to be used for any special offers or promotions, as that should be done in a scheduled message to new subscribers.
In the field for "Second Time Opt-In Message", enter a message to subscribers that have previously unsubscribed, and are re-subscribing. They'll receive this message immediately when they opt-in. This is usually something along the lines of "Welcome back to our mobile club." This is not to be used for any special offers or promotions, as that should be done in a scheduled message to new subscribers.
Click the Save Changes button at the bottom of the screen.
Text Message Example
Keyword: Tans
Opt-In Message: Thanks for joining the Seattle Sun Tan Deals list!
Additional Notes
If you're looking to change the quantity of messages that is disclosed to new subscribers in the opt-in message, see this post.
The opt-in message is not to be used for any special offers or promotions, as that should be done in a scheduled message to new subscribers.