MMS pictures won't send with iOS 11.3

I have an iPhone X and I've been using Mint since last November. In the last week or two, MMS pictures will not send to a non-iphone user. I get "message failed to send" messages when I try to text a picture.

I've gone and touched up my settings as described in the Mint tutorial, and restarted my iphone multiple times. It's not fixing it. Anybody else seeing this?

2 replies

I have upgraded to iOS 11.4, checked my cellular data settings to make sure they are right, and the problem is still there. I can't text pictures. 😞
Update: I made a typo in the URL I entered for MMSC. With that fixed, things are working again.