What is List-Unsubscribe?

There are several elements to juggle in the world of email as we come up with a new technique. From open rates and segmentation to your deliverability optimization, some things can easily fall through the cracks. However, one of the elements that cannot be legally allowed to be forgotten is the unsubscribe link in every commercial email communication you send.  

The optional email header, list-unsubscribe, let the recipient of the email opt out of getting emails without clicking on the unsubscribe link or reporting it as spam. In addition, through list-unsubscribe, the reputation of the email senders can be protected.

Before we get into the details of how list-unsubscribe functions and the best way to utilize it, let us first highlight why unsubscribe links might be necessary. 

Through Congress, the United States passed the Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003, otherwise known as the CAN-SPAM Act, to restrict and reduce the increase of uninvited emails in the early 2000s. In addition, the CAN-SPAM act outlined restrictions on how to send commercial emails and provided some degree of privacy to email recipients. 

The 2003 CAN-SPAM Act continues to be in effect up to today. In addition, commercial emails are defined by the FTC as every “electronic mail message the… purpose of which is the commercial advertisement or promotion of a… product or service.” Thus, if an organization sends any commercial emails, CAN-SPAM and the legal necessities of commercial bodies should be a massive part of how the email strategy is approached. 

Under the 2003 CAN-SPAM Act, every business that uses emails for remunerative purposes must adhere to the following seven elements;

  1. Do not utilize any false or misleading information in the headers of the email.
  2. Do not utilize deceitful language in the subject of the email.
  3. Conspicuously and clearly show advertising messaging as such
  4. Disclose the business location to the recipient.
  5. Inform email recipients how they can opt-out of such communications in future.
  6. Respect the request to opt-out and quickly handle them. 
  7. Be conscious of what is done by third parties on behalf of your business. 

The most significant one in the list and is known and loved (or hated) by many is the fifth one, telling the recipients how they can opt-out of such communications in the future. This is the model utilized in making sure that every commercial email has opt-out or unsubscribe options incorporated in all the sent messages. Regardless of your personal feeling about opting out, a link or unsubscribe option is mandatory for all emails. 

The opt-out or unsubscribe option can be offered to the recipient in several ways. Usually, the sender will include a link in the email footer along with a mailing address. For example, the image below shows a picture of a Twilio SendGrid internal email. It includes the address of the Denver office and opt-out options, as shown by the arrow in red. 

Nonetheless, there are various options aside from the footer link at the disposal of the sender as they fulfill this legal requirement. This includes placing the unsubscribe directions or links in the email copy or utilizing optional headers such as list-unsubscribe. In general, list-unsubscribe is taken to be the best means of fulfilling the fifth CAN-SPAM element. 

Let us begin with Gmail

A majority of inbox providers utilize list-unsubscribe which includes iOS mail, Yahoo! Mail, Gmail, and Microsoft inboxes such as Outlook. Email senders can then opt for a single or two list-unsubscribe methods: http: or mailto:. 

TL; DR, mailto: is based on email, whereas http: is based on the web.

mailto: This list-unsubscribe type sends a request to unsubscribe in the form of emailing a particular email address.

http: This list-unsubscribe type makes use of an URL that takes care of the POSTs initiated by an unsubscribe.

All the inbox providers take care of list-unsubscribe differently and have varying expectations and requirements for senders with plans of using list-unsubscribe. Therefore, you should ensure you bear these instructions in mind during your strategizing.

Let us begin with Gmail

The list-unsubscribe Gmail header is seen as a hyperlink in a drop-down menu positioned adjacent to the “To” field shown by the arrow in red below. 

As a platform, Gmail takes list-unsubscribe to be a top practice that every sender should implement. Email senders with great sending reputations will realize the prime functionality of the tool. 

The list-unsubscribe of Gmail facilitates both http: and mailto: methods, providing senders with the chance to pick the one that serves best their email plan. Nonetheless, Gmail favors mailto: over http: and often recommends it to senders. 

What about Outlook and Microsoft?

To facilitate the list-unsubscribe option on their platform, it is necessary that senders have an excellent sending reputation in Microsoft. In addition, Microsoft will only allow a sender to use the mailto: technique when facilitating list-unsubscribe. 

iOS Mail

In the iOS mail, the list-unsubscribe header may be found located on top of the message above the information of the sender, as can be seen in the image below.

As in Microsoft, iOS Mail also necessitates the sender to use only the mailto: technique. 

Yahoo! Mail availability

Yahoo! Mail announced in November 2018 its incorporation of list-unsubscribe to its features. However, similar to iOS Mail and Microsoft, Yahoo! Mail can only facilitate the mailto: technique from senders. 

So what is the implication of all this to marketers?

Though having a conspicuous unsubscribe option above your messages may appear terrifying, you should not be concerned. On the contrary, having such a feature can be an excellent thing for your email program!

The list-unsubscribe option enhances a user’s experience by offering a simple unsubscribe button, aids in maintaining healthy and engaged contact lists and helps boost the sender’s reputation. 

Having the list-unsubscribe options in the header offers a simple opt-out for email recipients. This implies that there is no need for them to search long and hard to locate the unsubscribe link found in the footer or copy of your email if they are no longer interested in what is in the email communication. Junk or spam complaints can arise if you make it hard for the recipients to opt-out, potentially damaging sending reputation. The experience of users is improved with easier access to opting out, which can be an excellent thing with time for marketers. 

What of consumers?

As far as list-unsubscribe is concerned, you should bear in mind that it does not spare you from setting and adhering to your recipients’ email expectations. You still have to consider giving recipients the opportunity of telling you the emails they prefer as they subscribe. Our Email Benchmark and Engagement study conducted in 2019 found that email recipients astoundingly prefer giving their choices as they opt-in compared to any other instance. By respecting the preference of your recipients from the very first point, you have a greater probability of having better engagement rates compared to sending every person in your contact list all messages you send at all times you send them. 

If emails that were not anticipated are getting to the recipients or emails they did not sign up for, the likelihood of them unsubscribing becomes greater. 

Sidebar: If you own an organization that works with or relays commercial emails to the European Union, restrictions are in place that governs to whom and how certain messaging can be sent under the GDPR – General Data Protection Regulation. Please look at our blog on the General Data Protection Regulation for all you should bear in mind as you work with EU citizens. 


To ensure that every Twilio SendGrid customer adheres to CAN-SPAM and other worldwide recipient privacy rules, we recommend every email has an active opt-out link. This is a best practice for senders and significantly boosts your recipients’ user experience. There are many possible advantages.

For those who use our subscription tracking, the http: and mailto: techniques are already incorporated into your messages’ headers. However, if you are not using our subscription tracking, you will be required to add the two methods manually for your organization to utilize the list-unsubscribe option. 

For a detailed analysis of list-unsubscribe support and our subscription tracking, please take a look at the list-unsubscribe article that can be found on our Knowledge Center. For further information on the best practices and how you can reap maximum benefit from email programs, check our blog for additional advice.