Confirm send & No attachment
I often compose a large business mail which is important and I alter and extend the content multiple times. And it happened to me multiple times, that I accidentally send the mail before it was finished. It would be great if there's an option which we can active for every mail, that when I hit the send button, a confirmation window shows up if we are sure, that the mail should be sent out.
Also, I often write in mails "I've attached you the document in this mail" etc. and then forget to add the attachment, please implement something like google mail, which detects this sentence inside the mail and when you want to send one, and you don't have an attachment added, it notifies you.

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GMS commented
Amen i love this program but i already have been embarrassed by accidentally hitting enter in the middle of a professional email. If there is no way around i will have to use something that offers this basic feature, i love the program but sending half complete drafts in a professional setting is a no go. My advice is to bind this prompt to the keyboard send action but not when clicking on the send button manually. When someone clicks on the send button they have show clear intent to send, on a keyboard not so much.