Twilio is unable to process your Toll Free Verification request because it could not be validated by Twilio and could not be submitted for verification review.
The toll-free phone number cannot be verified because the email address is invalid. It could be due to:
Correct the email address and resubmit the verification in Console via the Messaging Compliance API. It is not recommended to delete the verification to resolve email validation issue.
Forbidden message categories
https://support.twilio.com/hc/en-us/articles/360045004974-Forbidden-message-categories-for-SMS-and-MMS-in-the-US-and-Canada
Toll-Free best practices can be found at
https://support.twilio.com/hc/en-us/articles/360038172934-Information-and-best-practices-for-using-Toll-Free-SMS-and-MMS-in-the-US-and-Canada