Today because my patience was short, I removed as much of Mail's capability from my iPhone and iPad. The reason is that syncing just doesn't work from Mac to iOS. Using an iOS device to try and recall an email is pointless as so many emails just aren't carried over if I send a mail from my Mac. They are synced the other way around.
Then once that becomes a pointless task, I realised I don't actually need any email on my phone. I don't need to have something else to tend to once I buried the app and turned off its ability to grab email.
Should have simplified ages ago. This is much better.