If I open any Office document and select the option to Send/Email the message
a w message opens, I can compose the Email; but the window remains open after
I hit send with a message "This message has not been sent".

It appears frozen, I can close the email -- pressing the x.
I see the email in my sent and the mail is actually sent.

Is there a fix / patch to close and send the mail when I press send?

It makes it look like the mail is not sent so users are sending the emails
mutliple times.