Some disappear and get never sent out!

This is really awfull. I've sent a lot of messages for which I never got a response. When I look into the sent message list, the message is gone!

This happens only when a new message is sent, not when replying.

It is really stupid, that it is necessary to scroll down and hit 'send' a 2nd time for no reason. Also, I can't see that the message did not sent off until I scroll down!!!

Ah I see, Submit gives a Preview anyway. Put it on the todo list.

is it like that by design of phpBB or actually a bug?

I don't know. Could be both.

Old ticket closed. This is phpBB behaviour, if you enter a recipient but don't click the Add button, the recipient is looked up and added by Submit.