not with a mailto url that I know of
the URL handler just takes the URL and knows what to do with it - open mail & create a new mail with the right to, from, cc, bcc etc fields already filled in
The user has to actually click send
I did notice on SO there were some users also wanting to send emails automagically and there just didnt seem to be a decent way with whats exposed to Swift
One commented they used postfix, another mail service that is often running locally, to do that
seems crazy since I think you could do this with AppleScript
see AppleScript to send e-mail, using Apple's Mail, with multiple recipients, cc, bcc and attachments · GitHub
for source for such a thing
It might not be entirely silent as it will start mail if its not running
but you CAN do it so … it seems there should be a way in Swift
can swift send apple script commands to mail ?