Twilio Pipeline Retrieving Error Messages

What is the behavior you are seeing when an error occurs? Anything on your end? Or does the Pipeline just keep going like nothing happened?

Looking at the help doc on this it states that if you go over the rate limit it will kick you back an HTTP error so my thinking is there must be an HTTP error that is associated with other problems as well. Maybe that is all you would need to look for. The main issue as I am sure you have see is there are very little commands associated with this pipeline. You can basically send and receive messages. 

However looking into Twillios help docs now, you are probably in for a bad time. It says sometimes an error message can happen after the API has already accepted your request. So you are going to need to deal with many types of errors and it honestly sounds like this needs to be done in Twillio itself.

Twillio says the way it works is their will verify the data in your request is valid, as in yes that looks like a phone number and those bits are text. So just basic validation. Then after they accept it and enter it into their system they perform more validation and can find out that an entry is invalid at that point. In one scenario here there is no API level error returned at all.

I think what you will end up needing to do is to send all your SMS messages and then query Twillio for your recent message logs and then use those to determine if any of them failed and for what reasons. Hopefully you can find an easier way though.