Gets the DSN action type for the e-mail address.
The action performed by the Reporting-MTA taken from "Action" DSN field as a result of its attempt to deliver the message to this recipient address.
This field MUST be present for each recipient named in the DSN.
In this example, DSN field is:
Action: failed
The return value will be defined from the text marked bold.
DsnRecipient Class | MailBee.BounceMail Namespace