[xyzzy]

Hmm, ok. Not sure what's going on with my system then. Thanks for the quick feedback.

Based on what you said I tried using a different version of my Firefox browser (one I keep around with a relatively clean profile). It worked. I guess I didn't try that earlier. But...

Try sending a pdf attachment with the FM app. I still can't get that to work on my iPhone 13pro (using latest iOS 15.5). It demonstrates the same misbehavior as my main FF browser. The difference in tests between the app and using my browser on my computer is that on the computer I simply drag the pdf into the message I'm composing. On the iPhone I used the "attach from file storage" (paper clip) to get to the pdf I previously added to FM Files section. On the app, if I click it's save draft (click the X in upper left) the widow changes to the drafts and I can actually see it add the drafts folder and then it immediately disappears. Whatever is causing it to delete the draft is probably the same thing as causing the send to fail.

If it was just my main browser showing this behavior I wouldn't have been surprised since I use an out of date old version of Firefox with lots of add-on.* Lot's of pages have problems there where using a version with a clean profile it works almost certainly points my usual problems I have with this browser. Nothing new or surprising there. That would be the end of the story if it were not for the fact that I'm seeing the same misbehavior from the iPhone app.

[*I don't want to get into why I still am using an old out-of-date browser]