Watermarking and spoofed sender address

Kevin Miller Kevin_Miller at ci.juneau.ak.us
Wed Mar 20 16:20:34 GMT 2013

For what you're trying to do, SPF is a better option.

Kevin Miller
Network/email Administrator, CBJ MIS Dept.
155 South Seward Street
Juneau, Alaska 99801
Phone: (907) 586-0242, Fax: (907) 586-4500
Registered Linux User No: 307357
From: mailscanner-bounces at lists.mailscanner.info [mailto:mailscanner-bounces at lists.mailscanner.info] On Behalf Of Robert Lopez
Sent: Tuesday, March 19, 2013 3:58 PM
To: MailScanner discussion
Subject: Watermarking and spoofed sender address

I understand watermarking is to defend against "joe job blowback". I think I understand that blowback problem is when email is sent, using for example my address, to many other domains and all the flack (blow back) comes back to me.
I am wondering if this watermarking is of any use in a type of SPAM we now frequently see. It is where email is sent to a list of addresses, all at our domain, and the from address is also the first address in the address list. Everyone else thinks the first person sent it. Our gateways send such email to Exchange and any communication back to the sender is entirely within Exchange and never comes back through the gateways again.

In this kind of SPAM I have always considered it of no use. Am I wrong in my thinking?

Robert Lopez
Unix Systems Administrator
Central New Mexico Community College (CNM)
525 Buena Vista SE
Albuquerque, New Mexico 87106
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