French phrase
Merci de mettre ~ en copie.
Meaning
Please copy ___ on the email.
When to use it
A polite request to copy someone on an email. Common in professional correspondence when adding others to the thread.
Example dialogue
Merci de mettre Sophie et Paul en copie.
Please copy Sophie and Paul on the email.
Très bien, je les mets en copie.
All right, I'll copy them on the email.