This is a little time-consuming, but if sending picture mail is important enough to you, at least it will work, and you do not need to know the recipient's cell carrier. It takes advantage of the fact that Sprint does not allow incoming MMS mail on PPCs either and converts incoming MMS mail to a text message directing the recipient to the picture on a web site. However, it does require that the recipient have the ability to browse the internet.
1. Email the picture as an attachment to YOURSELF at
YourCellNumber@pm.sprint.com.
2. Sprint will place your picture on a web page and text message you with a link to the page
3. Forward that text message with the link, as a text message, to your intended recipient.
4. Recipient goes to the Sprint web page and views your picture