Add SMS blacklist, STOP to add to blacklist, START to remove from blacklist

Automatic Blacklist Addition: When users send "STOP" via the SMS channel, their phone number is automatically added to the blacklist, ensuring no further messages are sent to them.

Opt-in Removal from Blacklist: Users can rejoin the communication list by sending "START," which removes their phone number from the blacklist.

"Matched with Blacklist" Trigger: Utilize this trigger to engage users from different numbers when their phone number matches the blacklist.