macOS Sonoma Drops Support for Legacy Mail App Plug-ins - MacRumors
Skip to Content

macOS Sonoma Drops Support for Legacy Mail App Plug-ins

by

With macOS Monterey in 2021, Apple introduced a MailKit framework that developers can use to build modern and secure extensions for the Mail app on the Mac. Extensions can be created to block content, perform message actions, improve security, and more.

General macOS Mail Feature
In turn, Apple said legacy Mail app plug-ins would stop functioning in a future macOS release, and it appears that time has now come. AltStore today said it confirmed with Apple during WWDC last week that plug-ins are not supported on macOS Sonoma, and that MailKit-based extensions are the only supported solution going forward.


While MailKit extensions are more secure, they have more limited functionality compared to legacy plug-ins, so not all plug-ins may live on as extensions.

Legacy plug-ins cannot be opened in the Mail app as of the first beta version of macOS Sonoma. The update will be released to the public later this year.

(Thanks, @aaronp613!)

Tag: Apple Mail
Related Forum: macOS Sonoma

Popular Stories

MacBook Pro Low Angle Wide Lens

Apple to Launch 'MacBook Ultra' With These Six New Features

Friday April 24, 2026 10:32 am PDT by
While the 14-inch and 16-inch MacBook Pro were just updated with M5 Pro and M5 Max chips last month, bigger changes are reportedly around the corner. According to Bloomberg's Mark Gurman, the higher-end MacBook Pro models will be receiving a major redesign by early 2027, and he said that Apple might use "MacBook Ultra" branding for them. If so, the MacBook Ultra would likely be a...
Read Full Article • 160 comments
Dynamic Island iPhone 18 Pro Feature

This Is What the iPhone 18 Pro Looks Like

Saturday April 25, 2026 10:00 am PDT by
A recent leak provides our best look yet at the design of Apple's upcoming iPhone 18 Pro and iPhone 18 Pro Max models. Leaker Sonny Dickson recently shared images of the first iPhone 18 Pro, iPhone 18 Pro Max, and foldable iPhone dummy models. The images largely conform with rumors about the designs of the three devices and provide the first real visual confirmation of how they will look. ...
Read Full Article
app store monthly sub commitment

Apple Introduces App Store Monthly Subscriptions With 12-Month Commitment

Monday April 27, 2026 12:52 pm PDT by
Apple today announced the launch of a new subscription option for App Store developers: monthly subscriptions with a 12-month commitment. The new option allows developers to offer subscribers discounted pricing typically associated with an annual subscription but paid on a monthly basis to keep payments more affordable. This new payment option allows you to offer subscribers more affordable...
Read Full Article • 105 comments

Top Rated Comments

Max Webb Avatar
Max Webb
38 months ago
I didnt even know mail had plugin support full stop.
Score: 29 Votes (Like | Disagree)
redheeler Avatar
redheeler
38 months ago
Over a decade on MacOS and this is the first time I heard that the Mail app supports extensions.
Score: 26 Votes (Like | Disagree)
erikkfi Avatar
erikkfi
38 months ago

While MailKit extensions are more secure, they have more limited functionality compared to legacy plug-ins, so not all plug-ins may live on as extensions.
Apple loves doing this kind of thing -- see how they ruined Safari extensions -- and then they wonder why their native apps' usage stagnates rather than grows.
Score: 16 Votes (Like | Disagree)
D
ddauerbach
38 months ago
I'm really going to miss the really really useful SmallCubed Mailsuite suite of plugins.
Score: 11 Votes (Like | Disagree)
B
BarryTheWebdork
38 months ago

I'm really going to miss the really really useful SmallCubed Mailsuite suite of plugins.
I registered just to upvote this. SmallCubed is apparently going to release its own mail client now. So... well done, Apple.
Score: 8 Votes (Like | Disagree)
zorinlynx Avatar
zorinlynx
38 months ago
I still use Thunderbird because Apple Mail just isn't as capable. (Though I do use Apple Mail on my iPhone because the only mail client that was ever better on mobile was Sparrow and Google bought and killed that.)

People like to call Thunderbird "old" and "archaic" but E-mail hasn't changed much in 20 years. Thunderbird still does the job as well as it ever has, and they've recently started putting more development work into it so it will likely get even better moving forward.

Seriously, if you're a mail "power user", consider Thunderbird.
Score: 7 Votes (Like | Disagree)
Read All Comments