i'm sorry no one has responded to you. i don't know the answer to this one and apparently no one else has come across this particular issue either. maybe a little more info would help. are you using stock messaging or another messaging app?
I'm having the same problem. Regular text messages are sent without errors. Picture or slide messages are not going through at all. I can send a picture to myself and although I still get the error messages it sometimes comes through. Last week some of my pics were being delivered to other people despite the error messages I was getting but now nothing but a regular text will go through. Tried *228 and *22899 but nothing has changed.
Mine has been doing it for the last 6 months. Sometimes the picture will go thru and then I'll get these darn error messages for the next 10 minutes...sometimes longer. Sometimes picture doesn't got thru and I will get them. VERY annoying/obnoxious!
even tho you are sending emails through an app, it still uses the net to deliver your message try deleting your default browsers cache from the menu>settings>applications>browser , then do a 30sec battery pull.
Id be willing to bet, that'll work.