Marketo helps manage your data with the List Unsubscribe Header

Marketo Employee
Marketo Employee

What is it?

The List-Unsubscribe header is in the unseen header portion of email messages. Recipients don't see the header itself but if the receiving email network leverages the List Unsubscribe Header recipients will see an Unsubscribe button they can trust to unsubscribe from future messages. 

The header can look like this to receiving networks:


Subject: We need to implement this list-unsubscribe thing

Date: February 22, 2016 12:16:59 PM MST


List-Unsubscribe: <>


What is it important?

"The list-unsubscribe has been a very valuable tool for the email ecosystem, from consumers to businesses to mailbox providers. Over the past 20 years, consumers have slowly been trained to mistrust unsubscribe links located in the footers of email and spam, as some spammers would use the unsubscribe link to verify that the email address was a valid, active user. Once the spammers knew that, they would send them even more email rather than opting them out. In some cases, spammers would use the link as a way to install malware on an unsuspecting users’ machine."  Microsoft Changes List-Unsubscribe Requirements Melinda Plemel, 1/23/15


Does Marketo implement the List Unsubscribe Header?

Yes, for every email sent from our system Marketo leverages the mailto: List Unsubscribe Header function.


What networks are paying attention to the List Unsubscribe Header?

ISPs and spam filters view it favorably when making filtering decisions because having the List Unsubscribe header can indicate that the sender is actively working to avoid spam complaints. In fact, most major providers like AOL, Hotmail, Gmail, and Yahoo! support List-Unsubscribe functionality.

Looking specifically to Gmail, Gmail's Bulk Sender Guidelines recommend that the List Unsubscribe header be implemented.



How the List-Unsubscribe header works at Gmail

Gmail supports the List-Unsubscribe functionality and calls it “auto-unsubscribe.” Gmail inserts an Unsubscribe link next to the From Address.

Screen Shot 2017-02-23 at 2.08.58 PM.png


When an email recipient clicks on “Report Spam,” a dialog box will appear that asks if they want to unsubscribe or report the email as spam. If they click unsubscribe, a notification will be delivered to the email address in the List Unsubscribe Header to stop mailing you.

List Unsubscribe Example 2.png


Is this article helpful ?



Level 3

are list unsubscribes automatically included in every Marketo email or is it something that we need to set up?

Level 10 - Community Moderator

You don't need to set it up. It's always-on.

Level 3

Hi Kiersti Esparza​,

I recently used Litmus's new spam testing service in which they provide a seed list of about 20 email addresses for you to send an email to check for inbox placement, etc. Our email was flagged as not having the list-unsubscribe in the header, even though it was sent from Marketo.

I sent several more emails to a test inbox with gmail. I found that the unsubscribe header is sometimes included and sometimes not--even for emails using the same template (see screenshot).

Screen Shot on 2017-07-12 at 09%3A55%3A30.png

Is this a bug? Or is there a reason why some emails would be sent with the list-unsubscribe header and some not? Neither email is set to operational.

I appreciate your help!


Level 1


Technically the List-Unsubscribe header should be added to all standard emails.  There is a chance addresses may not see the header added, when we first implemented the header there was a bug in Hotmail/'s use of the header so we excluded them originally.  I believe that exclusion was rolled back when the bug was fixed. 

We do not typically add the header to test/sample messages however there is a bug where we see the header added to most test messages.  We are not looking to fix this bug because it can be useful sometimes when testing email content.

If the header is missing from an email that was sent as a standard part of the email campaign it is a bug.  If you wanted to report it through Marketo's Support channel I would recommend grabbing the email headers from those samples you show for deeper review.  Here's a Google site on how to find email headers in different providers: Message headers - Gmail Help

Thank you!


Level 4

Kiersti Esparza Is there an indicator in the activity log (preferably accessible to a filter/constraint) to know that the List Unsubscribe Header was the source of a user's unsubscribe action? Thanks.

Level 5

Thank you so much for this info!  If you, do come up with an indicator for these email client unsubs, it sure would be helpful.

Thanks again,

Level 2

I'm a little confused, because Deliverability Tools is telling us we do not have the list-unsubscribe, but from everything I am reading, we shouldn't have to worry about it and Marketo includes it by default. Is it possible that we could have accidentally removed the list-unsubscribe header on own?

Marketo Employee

Yes, the unsubscribe reason should display "List Unsubscribe."

Marketo Employee


It is possible that you are sending sample or test messages to the tool?  Marketo does not add the LU Header to test emails anymore, after an update a few months ago.

If you aren't sending tests, but live emails, this could be a bug.  Please reach out to Support so we can document this and escalate appropriately.

Thank you,


Level 2

That explains it. Thanks. Now we have to figure out why Amazon WorkMail is sending us to Spam 🙂