Change send mail shortcut to tab + enter in Apple Mail I'm looking for a way to change the default "send" shortcut in mail to "tab + enter" (like gmail)

I've found a way to change it to cmd + enterwith the following:

defaults write com.apple.mail NSUserKeyEquivalents -dict-add "Send" "@\\U21a9"

but doing something like: 

defaults write com.apple.mail NSUserKeyEquivalents -dict-add "Send" "\\u21E5\\U21a9"

Does not work. 

I've followed this answer, but I am unable to add the tab key in the shortcut dialog, and would prefer to do it from the command line. 

Thanks!
Because tab isn't a modifier key (like command, shift, option and control), you can't use it in combination with other non-modifier keys to make a shortcut. It's simply not possible the way the OS X input systems work AFAIK.

You might be able to jury-rig something together using KeyboardMaestro or similar apps that listens for tab-return and then executes the send mail command, but I don't know how well it would work, or how closely it would match your expected behaviour.