A web-based interface is often available to allow people to subscribe, unsubscribe, and change their preferences. However, mailing list servers existed long before the World Wide Web, so most also accept commands over email to a special email address. This allows subscribers (or those who want to be subscribers) to perform such tasks as subscribing and unsubscribing, temporarily halting the sending of messages to them, or changing available preferences - all via email. The common format for sending these commands is to send an email that contains simply the command followed by the name of the electronic mailing list the command pertains to. Examples: subscribe anylist or subscribe anylist John Doe.
Did you see that? Did you see it move? Pretty cool, right? This small bit of animation helps to separate this email from Tory Burch from all of the immobile emails in their recipient's inboxes. They also leverage exclusivity by framing the promotion as a "private" sale. Often times, this type of positioning makes the recipient feel like they're specially chosen, which encourages them to take advantage of the special opportunity they've been presented with.
A tracking pixel is a snippet of code that allows you to track your subscribers’ activity across various channels like your website, landing pages, and newsletters. Then, you also have the option to send emails triggered by certain behaviors. So for example, if a subscriber goes to your site and checks out your product page, a tracking pixel can send an email with a special offer for the specific product the viewed.