"X-Mail-from:" ; fastmail.fm
"X-MAIL-INFO:" ; NetZero
"X-Mailer_"
- "X-MailFlowPolicy:" ; Cicso ironport (http://www.ironport.com)
+ "X-MailFlowPolicy:" ; Cisco Email Security (formerly IronPort; http://www.ironport.com)
"X-Mailing-List:" ; Unknown mailing list managers
"X-MailingID:"
"X-Mailman-Approved-At:" ; Mailman mailing list manager
"X-Scanned-By:"
"X-Sender-ID:" ; Google+
"X-Sender:" ; http://people.dsv.su.se/~jpalme/ietf/mail-headers/
- "X-Sendergroup:" ; Cicso ironport (http://www.ironport.com)
+ "X-Sendergroup:" ; Cisco Email Security (formerly IronPort; http://www.ironport.com)
"X-Server-Date:"
"X-Server-Uuid:"
"X-Service-Code:"