Thanks for getting back to me. Turns out I had left "Auto-retrieve IP address" unchecked when changing back to internet2.voicestream.com. Not sure why I thought that was unchecked in the first place. Lack of sleep maybe? I thought I had either "broken" something or T-Mobile had flagged my account for something. I now have it all working under the T-Mobile Internet (GPRS) connection using epc.tmobile.com, although I have both "Use proxy" and "Automatic configuration" checked. Am now able to both send and receive MMS messages!! Nicely done everyone (frals especially)!