What Is a Newsletter?

A newsletter is an email a brand sends on a fixed schedule, weekly, biweekly, or monthly, to a list of people who agreed to receive it. It differs from a transactional email, such as an order confirmation, and from a one-off campaign: a newsletter has a recurring send date and a recognizable format, with sections that repeat issue after issue.

In the European Union, sending a newsletter to a consumer generally requires prior, freely given, specific consent, with a narrow exception for existing customers in some countries. That consent is usually recorded through double opt-in: the person signs up and then confirms through a link in a separate email, so there's a record that the address belongs to them and that they actually want the emails.

Content varies by industry: a roundup of blog posts, product updates, offers, or some mix of the two. What keeps the format working isn't its structure but the real value each issue brings to the subscriber.

Of the three, open rate is the one that can be taken least literally since Apple changed how it treats images inside an email.

The classic way to measure whether someone opened a newsletter is to embed an invisible tracking pixel in the email's HTML. When the mail client loads that image, the sender's server logs the request and counts it as an open. A click on a link is measured differently, through a parameter appended to each URL in the email that identifies the send and the subscriber.

That pixel mechanism became unreliable starting in September 2021, when Apple released Mail Privacy Protection (MPP) with iOS 15 and macOS Monterey, after announcing the feature at WWDC that June. According to Apple's own documentation, with the feature turned on, remote content in an email, images included, downloads in the background as soon as the message arrives, not when the person actually opens it. The pixel always loads through an Apple-run server, regardless of whether the recipient ever reads the email or deletes it unread. On top of that, Apple hides the recipient's real IP address from the sender during this process, so that figure no longer offers a reliable clue about region or device either.

The result is that some of the recorded opens don't correspond to a real read, but to that automatic preload. Open rate climbs artificially and stops working, on its own, as a reliable metric for any list with subscribers on Apple Mail. This distortion affects the classic pixel measurement specifically; click-through rate still only counts genuine interactions.

Because open rate no longer distinguishes a real read from an automatic preload, click-through rate becomes the more honest of the two: a click requires someone to have actually read something in the email and decided to act, something a proxy server can't do on their behalf. Conversion rate after that click, meaning how many of those clicks end in a purchase, a signup, or whatever action was the goal, completes the picture and ties the newsletter to a real business outcome.

Unsubscribe rate works as a warning signal in the opposite direction: a spike after a change in frequency or tone often flags, earlier than any other metric, that the content stopped matching what the list expected.

A newsletter is also one of the central tools for nurturing a relationship with a customer across their customer journey and raising their customer lifetime value: a well-segmented send keeps a brand present between one purchase and the next, especially relevant inside an inbound marketing strategy, where the newsletter nurtures a contact captured through another channel until they're ready to buy.

• Use double opt-in on the signup form so you can prove the person gave their consent and that the address is correct.
• Track click-through rate and conversion rate as the main metrics, and treat open rate as a rough reference, not the number that decides whether a campaign worked.
• Segment the list by interest or behavior instead of sending the same content to every subscriber.
• Log in a CRM what each subscriber opens and which links they follow, and adapt future sends to that behavior.
• Watch unsubscribe rate after every change in frequency, subject line, or design, and roll back the change if it climbs noticeably.
• Keep a consistent send frequency, stated on the signup form itself, so no one expects one thing and gets another.

• Reporting open rate as the sole success metric for a campaign, without accounting for the distortion Apple has introduced since 2021.
• Comparing the open rate of two campaigns with very different shares of Apple Mail subscribers.
• Sending a newsletter without double opt-in to a purchased or third-party list with no verifiable consent.
• Ignoring a sustained rise in unsubscribe rate instead of checking what changed in the content or the frequency.
• Sending the same newsletter to the entire list with no segmentation, even when the CRM already holds enough data to tailor it.