Ultimate Guide to Unsubscribe and List-Unsubscribe

by Anil Jalela | Oct 3, 2025 | Linux

The Ultimate Guide to Unsubscribe and List-Unsubscribe Best Practices.
Email deliverability is built on trust. One of the clearest ways to show respect for your subscribers is to give them a clear, simple, and standards-compliant unsubscribe option.

This isn’t just about compliance with laws like CAN-SPAM, GDPR, or CASL. A frictionless unsubscribe flow lowers spam complaints, improves sender reputation, and aligns you with strict requirements from mailbox providers like Gmail, Yahoo, Microsoft, and Apple.

In this guide, we’ll take a deep dive into:
– The RFC standards that define unsubscribe
– Provider and client support (mailto vs HTTP)
– Why RFC 8058 solved the infamous ‘bot problem’
– GET vs POST unsubscribe methods
– ESP and custom infrastructure requirements
– What the future looks like for unsubscribe management

1. What Is a List-Unsubscribe Header?

A List-Unsubscribe header is an email header that tells inbox providers how a
recipient can unsubscribe. Instead of hunting for a link buried at the bottom of an email, subscribers see a native ‘Unsubscribe’ button or banner inside their client.

Example: Gmail shows ‘Unsubscribe’ next to the sender’s name at the top of the message.

A simple header might look like:

List-Unsubscribe: <mailto:[email protected]>,
                  <https://example.com/unsub?id=12345>

Modern one-click headers use RFC 8058:

List-Unsubscribe: <https://example.com/unsub?id=12345>
List-Unsubscribe-Post: List-Unsubscribe=One-Click

2. What Do the RFCs Say?

The big leap came with RFC 8058, which fixed the ‘bot problem.’

3. RFC 8058: Solving the Bot Problem

Before RFC 8058, unsubscribe URLs often used GET. Security scanners, spam filters, and anti-virus bots routinely pre-clicked every link in incoming mail. This meant users could be unsubscribed without ever choosing to opt out.

RFC 8058 defined One-Click Unsubscribe via POST:
1. Sender includes two headers:
   List-Unsubscribe: <https://example.com/unsub/opaque-id>
   List-Unsubscribe-Post: List-Unsubscribe=One-Click

2. The recipient’s mail client performs an HTTPS POST to the unsubscribe endpoint with a body of:
   List-Unsubscribe=One-Click

3. The sender’s server unsubscribes only on valid POST requests.

Why it works:
– GET requests from bots are ignored.
– Only POST requests with the specific body trigger unsubscribes.
– No cookies, redirects, or extra parameters are allowed.
– DKIM signatures must cover the unsubscribe headers for authenticity.

4. Who Supports List-Unsubscribe?

5. Mailto vs HTTP Unsubscribe

6. GET vs POST Unsubscribe

GET: Quick but unsafe. Bots trigger unsubscribes accidentally.
POST: Requires explicit user action. Safer and compliant with RFC 8058.

Example GET:
GET /unsub?id=12345

Example POST:
POST /unsub/opaque-id
Body: List-Unsubscribe=One-Click

Gmail and Yahoo now enforce POST only.

7. ESP and Custom Infrastructure Requirements

Major ESPs like Mailchimp, SendGrid, HubSpot, and Amazon SES automatically insert unsubscribe headers, manage suppression lists, process feedback loop complaints, and offer preference centers.

If you self-host using Postfix, PowerMTA, or KumoMTA, you must:
– Generate List-Unsubscribe and List-Unsubscribe-Post headers
– Maintain a suppression database
– Accept POST-only unsubscribe endpoints
– Reject or safely handle GET requests

8. The Future of Unsubscribe

Gmail – Moving toward centralized ‘Manage Subscriptions’ dashboard.
Yahoo – Testing an ‘Unsubscribe Folder’ for bulk opt-outs.
Microsoft – Uses unsubscribe signals to sort Focused vs Other vs Junk.
Apple – Prominent unsubscribe banners in Mail, privacy-first focus.
ESPs – Blocking campaigns without headers, expanding preference centers.

9. Best Practices Checklist

– Include both mailto and HTTP unsubscribe
– Implement RFC 8058 one-click POST
– Sign headers with DKIM
– Ignore GET requests for unsubscribes
– Maintain a suppression list with reason codes
– Offer preference centers when possible
– Monitor Gmail Postmaster and Yahoo rules closely

Final Word

Unsubscribe is not the end of a relationship. It is part of a healthy one. By making it easy to leave, you strengthen engagement with those who stay. RFC 8058 gave the industry the tools to separate real human intent from bot noise. Gmail and Yahoo made it a requirement, and the rest of the ecosystem is following.

For any sender serious about inbox placement in 2025 and beyond, unsubscribe is no longer optional. It is mission-critical.

Gmail Postmaster Moving to v2 and Preparing for the Future

by Anil Jalela | Sep 26, 2025 | Linux

Google is retiring the original Gmail Postmaster Tools (v1) and replacing it fully with Postmaster Tools v2. Starting September 30, 2025, the v1 interface will no longer be available, and all users will be redirected to the v2 dashboards. At the same time, the existing v1 API—still in use by most deliverability platforms—will also be retired once Google launches the new v2 API, expected before the end of 2025.
Google Support Announcement

v1 vs v2 Interface: What’s Changing

Google Deal Cards Post-Open

by Anil Jalela | Sep 11, 2025 | Linux

Google Deal Cards Post-Open – What Marketers Need to Know
Google is reshaping the email marketing landscape with Deal Cards Post-Open, a feature that highlights promotional offers directly inside opened emails. Unlike inbox-level previews, this feature lives inside the email itself and gives brands a new opportunity to capture attention once a user decides to open.

What Are Deal Cards Post-Open?
When a recipient opens a promotional email in Gmail, a deal card may appear at the top of the message. These cards summarize the offer in a visually distinct way, often highlighting discounts, limited-time promotions, or seasonal sales.
This is not an AI-generated preview. It is a marketing-driven enhancement that allows brands to surface their key offers immediately after the email is opened.

When Do Deal Cards Appear?
Deal Cards are shown only in specific situations. Gmail may display them when:
The email is categorized under the Promotions tab
A user opens the email and Gmail detects a clear promotional offer
The offer is well-structured and easy for Gmail to parse, such as a percentage discount, coupon code, or sale event
The sender has a good reputation and meets Gmail’s technical requirements
They are not guaranteed to appear for every email. Gmail decides when to display them based on the content, structure, and trustworthiness of the sender.

Requirements for Deal Cards

Marketers must follow certain requirements to increase the likelihood that Gmail will generate Deal Cards for their promotions.

1. Use Promotional Schema Markup
   Implement Gmail’s supported email markup, either JSON-LD or microdata, with the PromotionCard schema. Key fields include discount amount, discount code, valid dates, and a short description of the offer.
   

2. Present Clear Offer Content
   Ensure the offer is visible and explicit in the email body. For example, “20% off until August 15” is more effective than vague wording like “great deals inside.”

3. Maintain Strong Sender Reputation
   Only senders with a good reputation are likely to see enhanced features. If a domain has frequent spam complaints, Gmail may avoid showing Deal Cards.

4. Authenticate Emails
   Gmail requires proper authentication through SPF, DKIM, and DMARC. These signals confirm sender legitimacy and are essential for schema-based features.

5. Target the Promotions Tab
   Deal Cards appear inside the Promotions tab, not in the Primary or Social tabs.

Why Deal Cards Matter for Marketers
Enhanced Visibility.
Important deals no longer risk being buried in long templates. The card ensures the most attractive offer is seen first.
Improved Engagement.
Highlighting key promotions can increase click-through rates and conversions, especially during competitive retail periods.

Design Adjustments
Since Gmail is surfacing structured offers directly, marketers must ensure their markup and promotional details are properly implemented.

Greater Competition
Because Gmail controls what is displayed, brands must compete on clarity, value, and compliance with Google’s promotional requirements.

How Marketers Should Prepare

• Add promotional schema markup correctly so Google can identify and display deals

• Keep offers simple, specific, and compelling to improve visibility

• Test and optimize wording for clarity, since short and precise descriptions work best

• Track engagement metrics to understand how Deal Cards influence click behavior

Final Thoughts

Deal Cards Post-Open create an additional layer of marketing visibility inside the Gmail experience. They reward marketers who provide clear, valuable, and well-structured offers while penalizing vague or poorly formatted promotions. By implementing schema markup, maintaining good sender reputation, and focusing on transparent promotions, brands can take advantage of this feature to strengthen engagement and drive conversions