MMS proxy / MMS port
The MMS proxy and MMS port settings allow you to configure an HTTP proxy that will be used only for communicating with the MMS Gateway Server.
As with the MMSC setting above it, these will need to be set according to the settings provided to you by your carrier. If they are not set correctly, you may still be unable to send or receive MMS messages, and people who send you MMS messages may not be notified that you don't receive them.
In many cases a carrier won't need you to use a proxy to send or receive MMS messages. This information may be left blank unless you are informed otherwise by the carrier.