21652: Maximum subject length is 40 characters

Use a subject that is 40 characters or fewer. Twilio returns this error when the subject text in your message exceeds that limit.

• The subject line you sent is longer than 40 characters.
• Dynamic text pushed the final subject over the limit after your application built the message request.

• Shorten the subject to 40 characters or fewer before you send the message.
• Review the final rendered subject in your application and trim or abbreviate any text that makes it exceed the limit.

• Messages resource