This is what showed up in the Message Logs whenever I tried to send the message: "(Error: 30007) Message filtered Your message content was flagged as going against carrier guidelines." According to this guide:  
https://support.twilio.com/hc/en-us/articles/223181848-How-Does-Message-Filtering-Work- , if you collect 3 or more examples of Message SIDs that have the “undelivered” status with error 30007, and then contact the Twilio Support team, they can review your messaging and determine if an error was made. Thanks for the help guys!