I couldn't get MMS to work for me on the N5 in the UK, but I don't know if that's because I bought the US version of the phone my mistake, or because of something specific to the Hammerhead port, or because it just doesn't work at all on Sailfish.

In my experience, MMS is pretty flaky on Sailfish anyway - I can receive MMS messages on my Jolla phone, but not send them (EE, UK).