The most noticeable change is an unsubscribe banner that will now appear at the top of marketing emails.
Years ago, Gmail added an unsubscribe link in webmail and people freaked out. It's somewhat of a positive thing, because it provides users the ability to unsub rather than mark as spam, which can happen often. If someone wants to unsub, at least they won't mark it as spam and harm your reputation. This could also help to organically clean your list of non-engaged subscribers.
It's also a bummer because it's placed in the best real estate of the email - the top - which will take away from the available space for the content of your message. The first impression of your email will be important to get your readers' attention. Make sure your subject line and preheader text are engaging and relevant with the content of your message. Remove unnecessary content from the top of your email such as navigation, social, contact information, etc., and get right to the point. Your main message and main call-to-action paired with a relevant subject line and preheader text will provide the best experience for an opener.
Video is back
I didn't add an exclamation point after the title, because while it's cool that video is back, it's still rather unsupported across all inboxes and difficult to set up. The <video> tag used to be available in iOS, but Apple removed it for the past few versions. Now it's back. What do you think? Is this something you'd like to know more about? Let us know.
Remove Apple apps
On the last page of apps on my iPhone you'll find a folder called Junk. I plan on removing Maps, Weather, Tips, Watch, Health and Contacts (because why does this exist in two places!?). Point is, Apple will let you remove unwanted preinstalled Apple apps. It will be possible for users to remove the native Mail app, which may attract users to seek out other mail apps. The Apple Mail app has been known to have good support for responsive design, so it's important that your emails be optimized for mobile to account for the varying support of other third-party mail apps.
Make sure to take a look at the device usage of your subscribers to find out who will be impacted by these changes. iPhone remains the most popular device for opening emails, so consider optimizing your emails for the best experience.