How should one-click unsubscribe links handle GET vs POST requests?
Matthew Whittaker
Co-founder & CTO, Suped
Published 18 May 2025
Updated 17 Aug 2025
8 min read
The implementation of one-click unsubscribe links has become a crucial aspect of email deliverability, especially with new guidelines from major mailbox providers like Google and Yahoo. These changes aim to enhance user experience by making it easier to opt out of unwanted emails, thereby reducing spam complaints and improving sender reputation. However, a common technical challenge arises in how these links handle HTTP GET versus POST requests.
Mismanaging these requests can lead to significant issues, such as unintended unsubscribes triggered by bots or security scanners, which can corrupt your email list and impact your overall deliverability. Understanding the distinction between GET and POST, and implementing the correct handling, is fundamental for maintaining a healthy email program and ensuring compliance with industry standards like RFC 8058.
Understanding one-click unsubscribe and RFC 8058
One-click unsubscribe simplifies the process for recipients to opt out of mailing lists, moving away from multi-step confirmation pages. This ease of unsubscribing can significantly reduce recipient frustration and, consequently, lower spam complaint rates, which is a major factor in email deliverability and how mailbox providers view your sending practices. Mailbox providers interpret high spam complaints as a signal of unwanted mail, potentially leading to your emails being directed to the spam folder or even having your domain or IP address added to a blocklist (or blacklist).
The technical foundation for one-click unsubscribe is laid out in RFC 8058, which specifies the use of the `List-Unsubscribe` and `List-Unsubscribe-Post` email headers. These headers provide a standardized way for email clients to present an unsubscribe option directly within their interface, often as a prominent button next to the sender’s address. For example, Gmail’s one-click unsubscribe functionality largely relies on these headers. It's not just about compliance, but about creating a better experience that prevents your legitimate emails from being marked as spam.
The `List-Unsubscribe` header specifies the URL or mailto address for unsubscribing, while the `List-Unsubscribe-Post: List-Unsubscribe=One-Click` header explicitly tells the email client that a POST request should be used for a true one-click unsubscribe. This distinction is vital because it informs the receiving mail server how to interact with the unsubscribe link without triggering accidental unsubscribes during automated scans.
The critical difference: GET vs POST requests
The primary distinction between GET and POST requests lies in their intended purpose and how they transmit data. A GET request is generally used to retrieve data from a server. When you type a URL into your browser, you're typically sending a GET request. It’s idempotent, meaning multiple identical requests should have the same effect as a single one, and it should not alter server-side data.
In contrast, a POST request is used to submit data to be processed to a specified resource, often resulting in a change on the server, such as creating a new record or, in this case, unsubscribing a user. It is not idempotent, and repeated POST requests could lead to multiple actions. This fundamental difference dictates how unsubscribe links should be handled.
GET request behavior
When an email client, security scanner, or a bot visits an unsubscribe URL using a GET request, it should not automatically process the unsubscribe. The purpose of this request is typically to check the link or display a confirmation page. If a GET request immediately unsubscribes the user, it can lead to accidental unsubscribes. This can be a major problem for marketers as it means subscribers are opting out without their explicit intent, skewing data and impacting campaign reach.
POST request behavior
For a true one-click unsubscribe, a POST request is expected. When an email client or mailbox provider (like Microsoft) makes a POST request to the unsubscribe URL specified in the `List-Unsubscribe` header (and indicated by `List-Unsubscribe-Post`), it should immediately and silently unsubscribe the recipient. No further confirmation should be required from the user, as the request itself is the explicit signal to opt out.
Allowing a GET request to directly unsubscribe a user is a critical server-side bug. This can happen if the unsubscribe endpoint doesn't properly check the HTTP method before processing the request. Such a flaw exposes your unsubscribe mechanism to automated processes that might crawl links, unintentionally removing subscribers from your list.
Many security scanners, including those operated by major mailbox providers, regularly sniff links in emails using GET requests. If your server processes a GET request as a full unsubscribe, these automated scans can inadvertently clean your list of active subscribers. This creates false positive unsubscribes, leading to inaccurate subscriber counts and potentially missed opportunities for engagement.
Avoiding accidental unsubscribes and ensuring compliance
With the recent one-click unsubscribe requirements from Gmail and Yahoo, correctly handling GET and POST requests is not just a best practice, but a compliance imperative for bulk senders. Failure to comply can result in your emails being marked as spam or rejected outright, severely impacting your deliverability and domain reputation.
Accidental unsubscribes can lead to inaccurate subscriber data, making it difficult to gauge the true engagement and effectiveness of your email campaigns. It also means you could be losing valuable subscribers who never intended to opt out, leading to a diminished return on your email marketing efforts. This data integrity issue can cascade, affecting segmentation, personalization, and ultimately, revenue.
The risk of GET-triggered unsubscribes
If your unsubscribe link processes a GET request as an immediate unsubscribe, you're vulnerable to widespread accidental opt-outs. Automated email security scanners, antivirus software, and even preview panes in email clients often make GET requests to check the validity or safety of links. If these legitimate scans trigger an unsubscribe, it leads to a loss of subscribers without any user intent, skewing your metrics and potentially flagging your sending practices as problematic.
A properly implemented one-click unsubscribe mechanism must differentiate between a GET request, which should lead to a user-facing confirmation page, and a POST request, which should silently and immediately process the unsubscribe. This distinction is fundamental to prevent false unsubscribes and ensure your email list remains accurate and valuable.
Implementing the correct approach
To correctly implement one-click unsubscribe while adhering to RFC 8058 and satisfying mailbox provider requirements, your server must be capable of handling both GET and POST requests to the unsubscribe URL specified in your `List-Unsubscribe` header. This dual handling ensures that automated systems don't trigger unwanted unsubscribes, while real users can still easily opt out.
GET requests: When your unsubscribe URL receives a GET request, it should display an unsubscribe form or a confirmation page. This page should allow the user to confirm their intention to unsubscribe, typically by clicking a button or submitting a form. This prevents bots and scanners from accidentally unsubscribing users.
POST requests: Upon receiving a POST request, your server should immediately process the unsubscribe without any further user interaction. This is the true one-click functionality that mailbox providers expect, signaled by the `List-Unsubscribe-Post` header.
URL consistency: The same URL should be used for both GET and POST requests. The `List-Unsubscribe-Post` header simply indicates that the email client or mailbox provider should initiate a POST request for the one-click action.
Once implemented, it's essential to test your one-click unsubscribe functionality thoroughly across various email clients and scenarios. This ensures that the mechanism behaves as expected, preventing both compliance issues and unintentional unsubscribes. Proper testing will confirm that GET requests prompt a confirmation, while POST requests lead to an immediate unsubscribe.
For the GET request, the confirmation page should be clear, concise, and offer options beyond just a full unsubscribe, if applicable. For example, it could direct users to a preference center where they can manage their subscription settings without completely opting out of all communications. This provides a more user-friendly experience and can help retain subscribers who simply want to reduce email frequency or change topics.
Views from the trenches
Best practices
Always include both List-Unsubscribe and List-Unsubscribe-Post headers in bulk emails.
Ensure your server distinguishes between GET and POST requests for unsubscribe links.
For GET requests, direct users to a confirmation page or preference center.
Common pitfalls
Allowing GET requests to trigger immediate unsubscribes, leading to false positives.
Not including the List-Unsubscribe-Post header, which can hinder one-click functionality.
Using a two-click unsubscribe for the header link, which violates new compliance rules.
Expert tips
Validate your unsubscribe URL's behavior with various tools to ensure it responds correctly to both GET and POST.
Consider rate-limiting or adding CAPTCHA to GET-triggered unsubscribe forms to prevent abuse.
Log all unsubscribe requests, including the request method (GET/POST), for debugging and analysis.
Expert view
Expert from Email Geeks says that it's crucial to distinguish between GET and POST requests for unsubscribe links to prevent unintended actions from automated systems.
2024-05-24 - Email Geeks
Marketer view
Marketer from Email Geeks says that their server had a bug where visiting the unsubscribe URL with a GET request would immediately opt out the user, which caused issues with automated scans.
2024-05-24 - Email Geeks
Maintaining email program health
Properly handling GET versus POST requests for one-click unsubscribe links is more than a technical detail, it's a foundational element of sound email deliverability and compliance. By correctly implementing RFC 8058, distinguishing between how your server reacts to GET and POST, and ensuring that only POST requests trigger an immediate unsubscribe, you protect your subscriber list from unintended removals.
This not only maintains the integrity of your marketing data but also enhances sender reputation by demonstrating adherence to best practices and respecting user preferences. A robust unsubscribe process, free from accidental opt-outs, fosters trust with both your subscribers and mailbox providers, paving the way for improved inbox placement and overall email program success.
Microsoft) makes a POST request to the unsubscribe URL specified in the `List-Unsubscribe` header (and indicated by `List-Unsubscribe-Post`), it should immediately and silently unsubscribe the recipient. No further confirmation should be required from the user, as the request itself is the explicit signal to opt out.
