macOS Monterey to Support All-New Mail App Extensions, Plug-Ins Will Stop Functioning in Future Release

As part of WWDC this week, Apple introduced a new MailKit framework for macOS Monterey that enables developers to create Mail app extensions that block content, perform message and composing actions, and help with security.

mail app extensions macos monterey
There will be four main categories of Mail app extensions, according to Apple:

  • Compose: Extensions that provide new workflows when composing emails
  • Actions: Extensions that apply custom rules to incoming emails, such as an email being color coded, moved to a separate inbox, marked as read, or flagged
  • Content Blocking: Extensions that serve as WebKit content blockers for emails based on specific criteria in an email's HTML code
  • Message Security: Extensions that sign, encrypt, and decrypt emails when sending and receiving mail, with signed and encrypted icons below emails

Xcode 13, available in beta, includes a template for developers looking to create Mail app extensions on the Mac. The extensions can be built into existing Mac apps and can also be distributed through the Mac App Store, according to a WWDC session about MailKit, which is available on macOS only and not iOS or iPadOS.

In the WWDC session, Apple indicated that older Mail app plug-ins will stop functioning in an unspecified future macOS release.

macOS Monterey is available now in beta for developers, with a public beta to follow in July.

Related Forum: macOS Monterey

Popular Stories

sonny iphone 16 pro colors

All Four iPhone 16 Pro Colors Revealed in New Image

Friday August 16, 2024 4:14 am PDT by
Leaker Sonny Dickson is back today with a new dummy unit image showing all four iPhone 16 Pro color variants, including the rose gold or "bronze" unit that replaces Blue Titanium in the existing iPhone 15 Pro models. The iPhone 16 Pro models are expected to come in black, white or silver, gray or "Natural Titanium," and a rose or rose gold color replacing Blue Titanium, according to Apple...
iPhone 16 Pro Right Side Feature

The iPhone 16 is Getting a New Button: Here's What It Can Do

Tuesday August 13, 2024 4:01 pm PDT by
Multiple rumors have suggested that the iPhone 16 models are going to have an all-new button that's designed to make it easier to capture photos when the devices are held in landscape mode. Apple calls the button the Capture Button internally, and it is going to be one of the most advanced buttons that's been introduced to date with support for multiple gestures and the ability to respond to ...
iPhone 16 Pro Sizes Feature

iPhone 16 Launch Is Just One Month Out – Here's Everything We Know

Saturday August 10, 2024 5:00 am PDT by
Apple typically releases its new iPhone series in the fall, and a possible September 10 announcement date has been floated this year, which means we are just one month away from the launch of the iPhone 16. Like the iPhone 15 series, this year's lineup is expected to stick with four models – iPhone 16, iPhone 16 Plus, iPhone 16 Pro, and iPhone 16 Pro Max – although there are plenty of design...
iPhone 16 Pro Sizes Feature

When Is the iPhone 16 Coming Out?

Wednesday August 14, 2024 6:20 am PDT by
Apple's iPhone 16 series is expected to debut in September 2024. This release follows Apple's trend of introducing new iPhone models annually in the fall. While the exact date has yet to be officially confirmed, the day of Tuesday, September 10 has been rumored as a possible announcement date, and September has traditionally been the month when Apple unveils its latest smartphone innovations. ...
maxresdefault

Apple Aiming to Launch Tabletop Robotic Home Device as Soon as 2026 With Pricing Around $1,000

Wednesday August 14, 2024 11:30 am PDT by
Apple is moving forward with its project to develop a tabletop robotic device, according to Bloomberg's Mark Gurman. Subscribe to the MacRumors YouTube channel for more videos. The device would feature a large iPad-like display mounted on a "thin robotic arm" that would allow the display to tilt and up and down and rotate a full 360º, and it would serve as a "smart home command center," a...
M4 Mac mini Silver Ortho Cooler

These New Macs Are Coming in 2024

Thursday August 15, 2024 4:34 pm PDT by
It's almost September, but Apple still has multiple new product launches planned for 2024. New iPhone 16 models and Apple Watches are coming in September, and we're also going to get at least three Mac updates with M4 chips this year, according to rumors. Here's what's on the horizon. MacBook Pro Apple plans to refresh both the 14-inch and 16-inch MacBook Pro models, adding M4 chips. The ...
T Mobile Generic Feature Pink 1

United States Fines T-Mobile $60 Million for Failing to Prevent Unauthorized Access to Sensitive Customer Data

Thursday August 15, 2024 1:32 pm PDT by
T-Mobile was fined $60 million by the Committee on Foreign Investment in the US (CFIUS) for negligence surrounding data breaches, reports Reuters. CFIUS penalized T-Mobile for failing to prevent or disclose unauthorized access to sensitive customer data. When T-Mobile merged with Sprint, it signed a national security agreement with CFIUS, which is what led to the fine earlier this year....

Top Rated Comments

cmaier Avatar
42 months ago

What we would like to get: correctly working gmail with most of its features in the native mail app
What we are getting:
Who is “we?” People who don’t care about their privacy, who demand that Apple support non-standards based protocols and functionality, and who work at Google?
Score: 24 Votes (Like | Disagree)
countryside Avatar
42 months ago
Can someone make an extension that lets us schedule a time for an email to be sent?
Score: 21 Votes (Like | Disagree)
kc9hzn Avatar
42 months ago

What we would like to get: correctly working gmail with most of its features in the native mail app
What we are getting:
To be fair, that’s mostly the fault of Google’s bizarre non-standard implementation of IMAP. Those features don’t really work on any app other than GMail.

As for the mail plug-ins, they were never a great solution. Apple will continually move away from systems like mail plug-ins that live in the memory space of another application to inter-application communication systems like extensions that allow an application to extend another application visually without sharing memory space MacOS Classic style. I, for one, am looking forward to having a mail extension system that provides a stable API and that doesn’t break with each point release.
Score: 13 Votes (Like | Disagree)
Peepo Avatar
42 months ago
Hope will be possible to tag a sender as not junk.
Score: 10 Votes (Like | Disagree)
kc9hzn Avatar
42 months ago

Same thing, different day, Apple can never find the original team that built a program, so they have to rebuild it from the ground up! lol
You do realize that Mail.app is a direct continuation of the NeXTStep Mail.app, yes? Which means that it’s nearly 40 years old. Most of the original team is probably retired by now.

But this is also a change that needed to occur. Previously, mail bundles would break between point releases. Not major releases, mere patches. Every time Mail.app got updated, these bundles needed to get updated, too, and, until they did, the bundles wouldn’t work. Now we have a stable API guaranteed not to break on point releases and that will likely be stable across multiple major releases. We’ll probably see more mail extensions as a result of this, while previously, it was only worth the effort to devs who were absolutely serious about email extensibility. This API could also be ported to MobileMail.app, which, until now, hasn’t had any extensibility (except maybe for jailbreaking, but even then, I don’t think Mail was a common target for jailbreakers looking to tweak the system).
Score: 6 Votes (Like | Disagree)
Graham King Avatar
42 months ago
It would be nice to be able to easily add HTML signatures. I might switch back from Spark if this is possible.
Score: 4 Votes (Like | Disagree)