I am using an HTC Snap with WM6.5 on T-Mobile.
When I have IM+ running, I am unable to send and receive MMS messages. I first noticed this when I was sending picture messages and they just sit in my outbox. I force a send and it looks like it starts to send, but after about a minute, it stalls out again. This continues until I close IM+. The message is immediately sent within a few seconds.
As far as receiving MMS, since failed MMS is set to resend to a device after a pre-determined time, I have done the following: With IM+ running, I will send an MMS to my device it does not arrive (waited approx 20 min). I will turn IM+ off and send an MMS and it arrive as my device within a couple minutes.
This may be a know issue but I am unable to locate any information about it.