[Grammar] return mail, returnd mail, return-mail

[uktous]

Hi,

Background:
If the postman fails to deliver our mail, he would return the mail to our office.

Question1:
How can we call such "mails"?
Question2:
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

Thanks

 

[Barb_D]

#2, but with the missing e: Returned mail.

Though I would suggest "undeliverable" mail.