Send Delay loses e-mails if closing Mail app too early

could not edit my original posting anymore when I recognized that this problem only occurs on iOS but not on MacOS. I therefore revised my posting as follows:

made some free testing for Apple ;)

I'm using "Send Delay" in Apple's Mail apps with a delay of 30 seconds.

Users should know and be aware of the fact/bug, that mails get lost if sender closes the Mail app on iOS before the message was actually sent in the background.

While such send-delayed message should preferably be automatically saved in outbox then, it instead disappears in nowhere and is lost.

If Mail app on iOS and MacOS loses internet connection during the delay phase, it saves the waiting message in the outbox. Same happens on MacOS if the Mail app is closed before a message was actually sent but that does not work on iOS.

Hope Apple will sometimes still take care of this....(and also still adds Mail app to the selection of available "topics" here in question setup. I had to go for "Apple ID" cause nothing else matches my topic at all.)