2.1.4.2 forward-path Field

The forward-path field MUST be set to the email address of a recipient of the original message. This address MUST be formatted in one of the following formats:

• An SMTP email address, as specified in [RFC2821].

• A DN address, as specified in section 2.1.1.<1>

Neither format is preferred over the other. The choice of format is left to the implementation.