List-Unsubscribe

Mail clients - why you should add an unsubscribe button

If you're an ISP that hosts webmail for users or a software developer that creates a mail client (MUA), then you should consider adding an Unsubscribe button to the UI. Including an Unsubscribe button for senders with a good reputation will reduce "false positive" spam complaints, reduce customer service requests, and improve the experience for your customers.

It has critical mass now and will make a difference for your users the day its implemented. By implementing the Unsubscribe button as an alternative to the Report Spam button, no additional screen real estate is needed and it remains a one-click command for the user.

Case study - Microsoft Windows Live Beta

Windows Live Beta has implemented an Unsubscribe button based on the List-Unsubscribe header. It still is in beta so things may change and may want to cut them some slack if some issues are still being sorted out.

In Windows Live Beta, there is an area just above the message headers that show the Subject and who the messages is From where informational messages are displayed. Most messages display a "Report & Delete" link - clicking on this reports the message to Microsoft as spam and adds the sender's From address to the user's personal block list.

If the sender's From address is in the user's address book OR the sender is in the ReturnPath Sender Score Certified program, the List-Unsubscribe header will cause an "Unsubscribe" link to be displayed instead of "Report & Delete".

When "Unsubscribe" is clicked, a message is sent to the address specified in the List-Unsubscribe header (only mailto is supported at this time) and the sender's From address is added to the user's personal block list. I'm worried that this behavior will confuse users when they try to resubscribe later.

List-Unsubscribe and Domain Keys / DKIM

The List-Unsubscribe header works very well with Domain Keys and DKIM. By placing the List-Unsubscribe header within the signed portion of the headers and message, receivers can be sure that the header is legitimate and has not been modified or falsified. As an additional safeguard, receivers might choose to only recognize List-Unsubscribe URLs whose domain name match the authenticated domain.

In this standard example, the List-Unsubscribe header is signed within the DomainKey signature and the URL within matches the domain that has been authenticated.

Domainkey-Signature: q=dns; d=EASE.LSOFT.COM; s=BETA1; c=nofws; h=Date:From:Subject:To:List-Unsubscribe; b=aetHboV7ctf903C4WKjpd4pfNe9PUOmErrfCwktSe7fdrc4c7H4FpGSSF2YUfYoeUEoHRxznKMia5rHTJL2Pah0t6WTCPirnyhzA3rJUz2ZxJH++Y75owoqrK4nzSM8D;
From: LISTSERV@PEACH.EASE.LSOFT.COM
Subject: SPAM-L Digest - 26 Aug 2006 to 27 Aug 2006 (#2006-245)
Date: August 27, 2006 10:00:19 PM CDT
To: SPAM-L@PEACH.EASE.LSOFT.COM
List-Unsubscribe: <mailto:SPAM-L-unsubscribe-request@PEACH.EASE.LSOFT.COM>


This List-Unsubscribe header is suspicious because it is not within the DKIM signature and goes to a different domain than the one that is authenticated.

List-Unsubscribe: <mailto:SPAM-L-unsubscribe-request@PEACH.EASE.ZSOFT.COM>
Domainkey-Signature: q=dns; d=EASE.LSOFT.COM; s=BETA1; c=nofws; h=Date:From:Subject:To:; b=aetHboV7ctf903C4WKjpd4pfNe9PUOmErrfCwktSe7fdrc4c7H4FpGSSF2YUfYoeUEoHRxznKMia5rHTJL2Pah0t6WTCPirnyhzA3rJUz2ZxJH++Y75owoqrK4nzSM8D;
From: LISTSERV@PEACH.EASE.LSOFT.COM
Subject: SPAM-L Digest - 26 Aug 2006 to 27 Aug 2006 (#2006-245)
Date: August 27, 2006 10:00:19 PM CDT
To: SPAM-L@PEACH.EASE.LSOFT.COM


Learn more about Unsubscribe at Lashback

Learn more about Unsubscribe from the Lashback blog

Google Gmail recommends List-Unsubscribe

From Google's Bulk Email Sender guidelines:

"Provide a 'List-Unsubscribe' header which points to a web form where the user can unsubscribe easily from future mailings (Note: This is not a substitute method for unsubscribing)."