Had to get a new sim and after that my Microsoft Messaging Application will no longer send or receive photos. Can't uninstall the application on my 950XL.
Do you have a MMS APN configured? Go to Settings > System > Phone, scroll down to the SIM section, tap Cellular & SIM, go to SIM settings, and scroll down to MMS APN. If there's nothing, try adding one. The info should be on your carrier's website, or do an internet search for your carrier's name + "MMS APN Windows 10 Mobile"