How do I add an unsubscribe header to emails in Intercom?
Matthew Whittaker
Co-founder & CTO, Suped
Published 18 May 2025
Updated 18 Aug 2025
6 min read
When managing email campaigns, especially with new sender requirements from providers like Google and Yahoo, the List-Unsubscribe header has become a critical component. This header allows email clients to display a prominent unsubscribe button to recipients, making it easier for them to opt out of unwanted communications. This is a key factor in avoiding spam complaints and maintaining a healthy sender reputation.
I often hear questions about how to implement this header when using various email service providers (ESPs). A common misconception is that you need to manually add HTML code to your email template to include this header. However, this is not how email headers function.
The List-Unsubscribe header is part of the email's envelope data, which is handled at the server level by your ESP. It's not something you embed directly within the HTML body of your email. This distinction is crucial for understanding how to ensure your emails comply with modern deliverability standards.
Intercom's automatic unsubscribe headers
Many email service providers, including Intercom, automatically manage the List-Unsubscribe header. This is a standard practice designed to improve email deliverability and reduce spam complaints. If your ESP didn't include this header, it could lead to higher complaint rates, increased blocklisting (or blacklisting), and ultimately, your emails landing in the spam folder.
Specifically, Intercom states that any email sent from their platform that is not a 1:1 message will always include a List-Unsubscribe header. This is a significant feature that helps you comply with email regulations and best practices without requiring any manual setup on your end.
Intercom also supports RFC 8058 one-click unsubscribe headers. This is particularly important for meeting the latest requirements from major mailbox providers like Google and Yahoo, which mandate one-click unsubscribe functionality for bulk senders. If your emails are sent through Intercom, it's very likely this functionality is already active.
Automatic compliance
Intercom automatically adds the List-Unsubscribe header to non-1:1 emails. This includes the List-Unsubscribe-Post header for one-click unsubscribe as per RFC 8058.
Deliverability: By handling unsubscribes efficiently, you reduce the likelihood of recipients marking your emails as spam, which helps maintain your sender reputation and prevents your domain from being put on a blocklist (or blacklist).
Compliance: This automatic inclusion helps meet the new sender requirements from providers like Google and Yahoo, which mandate easy unsubscribe options.
Verifying the unsubscribe header
Even though Intercom handles the List-Unsubscribe header automatically, it's always a good idea to verify its presence in your sent emails. You can do this by inspecting the raw email headers from a message you've received.
To check email headers in Gmail, open the email, click the three-dot menu next to the reply button, and select Show original. This will display the full raw message, including all headers. You should look for lines starting with List-Unsubscribe and List-Unsubscribe-Post.
These headers indicate that your emails are configured correctly for one-click unsubscribe functionality, which is crucial for modern email deliverability and ensuring your messages land in the inbox rather than being filtered as spam or triggering blocklisting (blacklist) actions.
Test emails vs. live emails
It's important to understand that test messages sent from an ESP might not always include the full set of headers that a live, production email would. This can sometimes lead to confusion when you're trying to verify specific email authentication or unsubscribe features.
Test emails
Test emails might lack certain headers, including List-Unsubscribe, because they are often routed differently or bypass some of the standard sending processes applied to bulk or campaign emails. This is generally because they are not considered part of a mailing list, which is what the header pertains to.
Live production emails
To confirm that your List-Unsubscribe header is present and correctly configured, it's best to check the headers of an actual email sent as part of a campaign to a real recipient. This provides a more accurate representation of how your emails are being handled by Intercom and mailbox providers.
If you're using Intercom for marketing or bulk email purposes, rest assured that the platform is designed to handle these technical aspects automatically, especially with the newer industry standards. The challenge often lies in verifying this, as test emails may not reflect the full production configuration.
Integration with other platforms
A common scenario involves integrating Intercom with other platforms, such as HubSpot, where contact lists and unsubscribe preferences might originate or be synchronized. Even in such setups, where a list might start in HubSpot and then be pushed to Intercom for sending, Intercom is responsible for adding the necessary headers to the emails it sends.
Your ESP (Intercom in this case) acts as the final sending agent and is configured to include the List-Unsubscribe headers and implement one-click unsubscribe. This is part of their core service to ensure your emails are compliant and have good deliverability. Unless you are using Intercom in a very unconventional way that bypasses its standard email sending mechanisms, you should find that it handles this automatically.
It's worth noting that while Intercom might be primarily seen as a customer support tool, its outbound messaging capabilities for marketing and transactional emails are robust enough to include critical deliverability features like these. This means you generally don't need to look for manual configuration options for the List-Unsubscribe header within the user interface, as it's handled on the backend.
Views from the trenches
Best practices
Ensure your contact lists are clean and regularly updated to avoid sending to invalid or disengaged recipients.
Always include a visible unsubscribe link within the email body, in addition to the header, for user convenience.
Monitor your sender reputation using tools like Google Postmaster Tools to identify potential issues.
Common pitfalls
Attempting to manually add List-Unsubscribe headers via HTML in email templates, which is ineffective.
Failing to synchronize unsubscribe data between different marketing and CRM platforms, leading to re-subscriptions.
Relying solely on test emails to verify header presence, as they might not reflect live sending configurations.
Expert tips
Verify unsubscribe header presence by checking raw headers of actual live campaign emails, not just test sends.
Keep an eye on RFC 8058 for one-click unsubscribe compliance, especially with major mailbox provider changes.
Understand that ESPs are responsible for adding email headers, as these are part of the email's technical envelope, not its content.
Expert view
Expert from Email Geeks says that headers are typically controlled by the ESP and exist outside the HTML container, so if an ESP doesn't offer this, it's a red flag.
2024-01-15 - Email Geeks
Marketer view
Marketer from Email Geeks says they use Intercom as a workaround to avoid paying for expensive marketing platforms, implying a non-standard setup.
2024-02-20 - Email Geeks
Key takeaways
The key takeaway is that you typically do not need to manually add an unsubscribe header to emails sent via Intercom. The platform is designed to include the necessary List-Unsubscribe and List-Unsubscribe-Post headers automatically for non-1:1 messages, ensuring compliance with modern email deliverability standards, including one-click unsubscribe.
While manual additions via HTML are not the correct approach for email headers, it's always prudent to check the raw headers of a live, sent email to confirm that these crucial elements are present. This proactive verification helps ensure your email campaigns maintain good standing with mailbox providers, avoid being put on a blocklist, and reach your recipients' inboxes effectively.
Focus on managing your email lists and content effectively within Intercom, knowing that the underlying technical requirements for unsubscribe headers are handled for you.
Gmail, open the email, click the three-dot menu next to the reply button, and select Show original. This will display the full raw message, including all headers. You should look for lines starting with List-Unsubscribe and List-Unsubscribe-Post.
HubSpot and then be pushed to Intercom for sending, Intercom is responsible for adding the necessary headers to the emails it sends.
