Go to the Reports (menu) > Find Reports > Email/Text/Marketing (left menu) > Text (tab) > Text Undeliverable Report to find messages that were undeliverable due to an invalid phone number or number that does not support text messaging or to find texts that were rejected by the number's phone provider as being suspicious or spam.
Save this as a frequently used report! Click the Heart iconnext to a report name, the heart will change to red
and the report will be listed under the Reports menu > My Reports for quick and easy access!