But anti- spam software often fetches all resources in mail header fields automatically, without any action by the user, and there is no mechanical way for a sender to tell whether a request was made automatically by anti-spam software or manually requested by a user. To prevent accidental unsubscriptions, senders return landing pages with a confirmation step to finish the unsubscribe request. A live user would recognize and act on this confirmation step, but an automated system would not. That makes the unsubscription process more complex than a single click.

Here are some recommended unsubscribe methods: Include a prominent link in the message that takes recipients to a page for unsubscribing. Let recipients review the individual mailing lists they’re subscribed to. Let them unsubscribe from lists individually, or all lists at once. Automatically unsubscribe recipients who have multiple bounced messages. Periodically send a confirmation message to recipients to make sure they still want to get your messages.

Let recipients easily unsubscribe Always give recipients a way to unsubscribe from your messages. Make unsubscribing easy. Letting people opt out of your messages can improve message open rates, click-through rates, and sending efficiency.

Also, make sure a user does not need to enter credentials or select a checkbox to complete the unsubscription process.

With the http method, behind the list-unsubscribe header, there is a URL leading to a web page for opting out. When a user clicks the unsubscribe link, a landing page opens, and the user is asked to confirm unsubscription.

Let’s say the recipient is considering unsubscribing. He or she may be too busy to search through the email to find the unsubscribe link, so he or she just clicks “Report as SPAM” to stop the emails from coming. This is the last thing any marketer wants to see happen. It negatively impacts sender reputation, requiring extra work to improve email deliverability. With the list-unsubscribe header, you will avoid getting into this kind of trouble in the first place.

So long as the filters are only using GET requests to pull down links, there’s nothing fundamentally wrong with them. It’s a basic (though oft-ignored) tenet of web development that GET requests should be idempotent; that is, they shouldn’t somehow change anything important on the server. That’s what POST is for. A lot of people ignore this for convenience’s sake, but this is just one way that you can get bitten. Anyone remember the Google Web Accelerator that came out a while ago, then promptly disappeared? It’d pre-fetch links on a page to speed up things if you clicked them later on. And if one of those links happened to delete something from a blog, or log you out… well, then you begin to see why GET shouldn’t change things. So yes, the perfect solution to this is a 2-step unsubscribe link: the first step takes to you a page with a form on it, and that form then POSTs something back that finalizes the unsubscribe request.

Two step unsubscribe, where the link in the email goes to a webpage with a prominent “click here to unsubscribe” button is often a good thing for unsubscription. It also gives people an option to not unsubscribe, when they click on the wrong link, or hit “return” with the wrong link focused, in a mail inadvertently, which isn’t that unusual in link-laden emails.

Arguably any link that performs such an action via GET is fundamentally broken. A proper unsubscribe should direct to a page with a form that requires a POST submission. (Of course, in the real world, few things are proper.)

Under CAN-SPAM, the ability to unsubscribe should be free and should not be behind a login process. This means that users must be able to unsubscribe without paying a fee and without needing to log into their account to do so