If the postman fails to deliver our mail, he would return the mail to our office.
How can we call such "mails"?
Can I call it whatever I like on my CV?
Possible choices (on my CV) :
1) Managing return mail
2) Managing returnd mail
3) Managing return-mail
#2, but with the missing e: Returned mail.
Though I would suggest "undeliverable" mail.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.