Last addition ;-) Rated 5 out of 5 stars

Thanks for adding the hot key! :)
But you're right. I guess my way to use the addon is kinda "unusual" ;) But I also didnt know about CTRL+SHIFT+ENTER. That would indeed solve my problem, too.

I guess my intended way was "enabled by default, but I can bypass it with 1 hotkey" instead of the other way around ;)

I dont know - maybe it would be better for beginners to add a list of shortcuts to the preferences. Or at least a link to the manual. Nevermind, now it's perfect ;)

This review is for a previous version of the add-on (3.3.2). 

Addition to my previous posting Rated 4 out of 5 stars

Sorry but I wasnt able to reply to your answer below.

Thanks for the hint regarding the hot keys. But am I correct that there is one missing for "send now"? That'd be the one I need most since I need the sending-later-feature only in some cases

Edit: Maybe you could add to the configuration that "CTRL + Enter" either sends at the specified time (as it is currently assigned) or sends immediately (without Send Later 3). That'd be great!

This review is for a previous version of the add-on (3.3.2). 

Shortcut will be added

I'm a little confused about your usage model, since unless you've enabled the "'Send' does 'Send Later'" option in the add-on's preferences, you can send immediately by hitting Ctrl-Enter when composing the message. Without that option set, the dialog will only pop up if you hit Ctrl-Shift-Enter.
Having said that, you're right that the "Send Now" button should have a shortcut key in the pop-up dialog, so I've added it as Alt-N (or the equivalent in other languages). You can download the 3.3.3beta1 beta release I've just uploaded with that change, or wait until I release version 3.3.3 to everyone and you'll get the change automatically.

Great addon! But: shortkeys? Rated 4 out of 5 stars

Love this addon!

But since I'm sending emails usually by hitting CTRL+ENTER, I was wondering whether you can add some shortkeys to control the Send Later popup with the keyboard? E.g. "ENTER" for sending without delay, "CTRL+[1]" for quick button 1, "CTRL+[2]" for quick button 2, and so on

Would be great!

This review is for a previous version of the add-on (3.3.2). 

Functionality already exists

http://blog.kamens.us/send-later-3/#hotkeys