A 17-digit voucher number is shown on the email sent by Frontier Airlines.
The email was sent to the email used on your earlier booking or the email attached to your Frontier Miles account with your voucher details.
*We recommend searching your email including junk or spam folders.
The subject line is “Your $XX voucher is here.”
The sender address was either email@example.com or firstname.lastname@example.org
Here is a sample email: