macOS/IOS iMessage not delivered.

Every now and then, I get the Message app starts doing a 'Not delivered' - this is almost always when I'm sending an image, but if there is a text message with it then they both get not-delivered. Doing a retry, sometimes works. The person getting the message is using an iPhone. No, they don't block me or anything.

This last time, I 'fixed' the problem by using my iPhone and taking a photograph of the string of failed attempts (both retry and retry as text message), and sending that in my iPhone.

I've tried capturing a screen shot using the Ctrl/Shift/Cmd/4 and pasting that into the app.. no luck.

And I've tried closing the app, and restarting.

Try again... 30 times and it doesn't go through...

Eventually, without doing anything else, I'm able to send again... and no, this is NOT on the other end with them blocking me or anything else.

Have had this issue for 2-3 YEARS now.

This issues has been on 2 different iPhones, and Mac Studio, Mac Pro, Macbook Pro...

When it gets screwed up, it doesn't work to multiple people...

(This idiot posting system said: "you have included content in your post that is not permitted. I assume this is a Donkey-Message that isn't smart enough to tell me WHAT isn't permitted!!)

25 minutes later, without changing anything, it is working again... (like it always does), this is NOT a problem with internet or anything, as I've had a solid FIOS connection to the internet the whole time...