Bounce Address Tag Validation (BATV) provides a mechanism for assessing the validity of an email's envelope return (bounce) address. It permits the original submitter of a message to sign the SMTP MailFrom address. This enables detection of invalid bounce addresses.

Wikipedia Excerpt

The basic idea is to send all e-mail with a return address that includes a timestamp and a cryptographic token that can not be forged. Any e-mail that is returned as a bounce without a valid signature can then be rejected. E-mail that is being bounced back should have an empty (null) return address so that bounces are never created for a bounce and therefore you can't get messages bouncing back and forth forever.

BATV replaces an envelope sender like mailbox@example.com with prvs=tag-value=mailbox@example.com, where prvs, called "Simple Private Signature", is just one of the possible tagging schemes; actually, the only one fully specified in the draft. The BATV draft gives a framework where other possible techniques can fit into. Other types of implementations, such as using public key signatures that can be verified by third parties, are mentioned but left undefined. The overall framework is vague/flexible enough that similar systems such as Sender Rewriting Scheme can fit into this framework.