Why is the Sender email id blank for some of the Emails in AntiSpam Quarantine report?
Sender email-id might be missing in following cases:
1. Email is a notification mail sent by the Mail server, for example: Undelivered email
Cyberoam follows RFC 2821 which states that notification mail sent by the Mail server
does not send the sender email id as it does not expect recipient to reply to that mail.
Hence Cyberoam does not display any email id in the “Sender” column of the Anti Spam
2. Invalid email composition (Spoofed)
Spammers spoof the email content by sending spoofed email header (MIME Header)
and valid email-id in the SMTP Protocol connection. To provide correct information,
Cyberoam does not use the information provided in MIME header as there are chances
header content spoofing .
Refer to http://www.ietf.org/rfc/rfc2821.txt?number=2821 section 6.1 Reliable Delivery and
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