Pertaining to the ongoing spam messages we all get, and all the apps that I use, how about adding a community spam submission button (spam option under the block option).
I am not sure if Textra keeps any sms data, but the idea is that the user community would send/submit a spam message (phone numbers or emails), and if say an excess of say 5 to 10 users submit the same message, Textra would filter it out as spam or block it.