Another fun fact: Chatty/mmsd-tng doesn't limit you to what file type you send/receive over MMS, provided it is under the attachment size limit. However, if you send wacky file attachments to iOS or Android, they won't recognize it due to limitations on their end.
If you are really adventurous, you can change the file attachment limit in mmsd-tng too (you need to hand edit the settings file).
(Carriers may impose a limits though, so YMMV. I only tested on T-Mobile USA).
In Case anyone is curious,
@craftyguy and I successfully sent an encrypted MMS via gpg!
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@kop316 @craftyguy
I'm still just trying to get mms to work. I can send but I still don't receive.
@jlcrawf @craftyguy
If you can send, mmd-tng is working, it sounds like there is an issue with the SMS WAPs you are receiving....