Alert message before sending

Is there a way to set up a rule that stops email from going to certain addresses?
I have a co-worker that keeps sending emails back to me when I forward them to him.

So, a rule that checks if the email is going to a certain address and preferably a popup that alerts the user that this maybe the wrong address, like “are you sure that you want to send this to x”?, would be fantastic to be able to set up.

Best regards
Robin Alfredsson

The best solution is just don’t forward messages to that recipient.

Unfortunately eM Client Rules only apply to sent messages once they have been sent. At that point the Rule can only affect the message in the Sent folder by deleting it, moving it to another folder, adding a tag etc.