I have an application sending SMS under user control (not a mass send). It is using the email gateway (@att.txt.net). The purpose is to send an appropriate URL for further assistance. If I send this URL: https://goo.gl/XqxRFe the message does not go through. If I send this URL: https://www.cnn.com the message goes through fine. This is a new problem. I get no "bounce back" from ATT explaining why the message is not delivered.