Iridium Mail APP help

[Epicurean]

My apologies for probably being in the wrong forum. I have some issues with Iridium's Mail App. I can transfer messages but they don't always appear in my Inbox. I don't know where they go. Hitting "Load more images" doesn't seem to do anything. Sometimes messages have appeared seemingly a day after being fetched.
Since I want this for weather routing missing a message or a day's delay could be catastrophic.
I also don't seem to have sent messages in my outbox. Are they saved? So I have no way of telling if a message was actually sent.
I attach a screen shot of my inbox header. What is the number "4"?
Thanks