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

Top Rated Comments

cmaier Avatar
30 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
30 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
30 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
30 months ago
Hope will be possible to tag a sender as not junk.
Score: 10 Votes (Like | Disagree)
kc9hzn Avatar
30 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
30 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)

Popular Stories

iPhone 16 Mock Header With Dynamic Island

Skipping the iPhone 15 Pro? Here's What's Rumored for iPhone 16 Pro

Friday September 22, 2023 9:29 am PDT by
Are you skipping the iPhone 15 Pro and waiting another year to upgrade? If so, we already have some iPhone 16 Pro rumors for you. Below, we recap new features rumored for the iPhone 16 Pro models so far:Larger displays: The iPhone 16 Pro and iPhone 16 Pro Max will be equipped with larger 6.3-inch and 6.9-inch displays, respectively, according to Ross Young, CEO of Display Supply Chain...
Update Your iPhone 15 to iOS 17

Warning: Update Your iPhone 15 to iOS 17.0.2 Before Transferring Data From Another iPhone

Friday September 22, 2023 6:36 am PDT by
If you are unboxing an iPhone 15, iPhone 15 Plus, iPhone 15 Pro, or iPhone 15 Pro Max today, make sure to update the device to iOS 17.0.2 before transferring data to the device from another iPhone, or else you might encounter issues. iOS 17.0.2 is only available for the iPhone 15 lineup. Apple says the update fixes an issue that may prevent transferring data directly from another iPhone...
iOS 17

Apple Releases iOS 17.0.1 and iPadOS 17.0.1 With Bug Fixes, Plus iOS 17.0.2 for iPhone 15 Models

Thursday September 21, 2023 10:28 am PDT by
Apple today released iOS 17.0.1 and iPadOS 17.0.1 updates for the iPhone and the iPad, adding bug fixes to the new software. The iOS 17.0.1 and iPadOS 17.0.1 updates come just a few days after Apple launched iOS 17 and iPadOS 17. The software, which is build 21A340, can be downloaded on eligible iPhones and iPads over-the-air by going to Settings > General > Software Update. There is a...
Apple Watch Ultra 2 double tap gesture 230912

watchOS 10.1 to Enable Apple Watch's New 'Double Tap' Gesture

Thursday September 21, 2023 12:52 pm PDT by
The new Double Tap gesture for the Apple Watch Series 9 and the Apple Watch Ultra 2 will be enabled starting with watchOS 10.1, according to Marques Brownlee, host of the popular tech-focused YouTube channel MKBHD. The first beta of watchOS 10.1 will likely be available by next week, and Apple announced that the software update will be released next month. Brownlee shared his impressions...