This is not an htc issue.
Look guys, the carriers arbitrarily compress and resize images being sent via mms. They have always done this. Its common knowledge.
If the mms goes from one carrier to another its likely to be reduced more.
Here are two different screen shot of the details of mms images from my friend's HOX, opened with the gallery, then display details :
Note that the size differs between that one and this one even though the images are the same resolution.
These were both sent and received on at&t using the international version of the One X.
MMS has no rules. Carriers can do pretty much what they want.
Sent from my HTC One X using Tapatalk 2