Apple deletes support for plug-ins

Just received an email from Houdah Software about the upcoming cooperative Summerfest and additionally, their support of Sonoma. Here’s a link to the web version:

They explain how Apple is dropping support of plug-ins in when Sonoma is released. This means Houdah Spot and Tempo will no longer be able to search’s database. This is also true of DevonThink Pro and its mail transfer function (at least there’s workarounds for this) and who knows how many other programs that rely on’s plugins. Thanks, Apple, for the reduced functionality. Hopefully you’ll be able to free up resources to increase your rate of ignoring major bugs and causing serious loss of functionality for your long term users, all in the name of producing more crapware like the nearly totally unused “stage manager.”

Don’t get me wrong–I greatly appreciate the real advancements Apple has implemented since Snow Leopard, including APFS with its security improvements and jaw dropping increases in speed (albeit with expensive hardware upgrades), as well as Apple silicon. But they have also completely wrecked the user interface and keep trying to force inane “upgrades” down our throats on an annual basis ( really??..etc.).

Oh well. It’s not like there are viable alternatives out there.


That is not exactly what Apple is doing. They have told developers that Mail Plugins will be required to be re-coded as Mail Extensions. From what I am hearing, that is not an easy task, so we will just have to wait and see what ones are ready to go on Sonoma release day this Fall, which are delayed or buggy and which have been abandoned.

BTW, MailKit extensions have been a thing for over two years now, so Developers could have been working on this since WWDC21.


Indeed, it was 2021 when Apple introduced extensions. It may even have been earlier when they first announced that plugins were going away.

I still haven’t gotten over the separate loss of Address Book plugins when Mojave was released. I had long used Brian Toth’s excellent PostCheck plugin to normalize US addresses to a standard format, and I’ve never found anything quite as convenient or effective to replace it.

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Yeah, I’ve been dreading this because in spite of Apple’s warnings about plug-ins going away, I still rely on the good old MailTrackerBlocker and so far have heard no news from its dev as to moving to MailKit.

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There’s now an extension for mailtrackerblocker.

I stopped using the plug-in with Ventura, since Ventura basically blocks mail trackers natively anyway.

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Woohoo, brand new. Now all I have to do is wait for it to be released outside of the App Store.

Edit: Just heard back from dev. Outside distribution is in the works. :+1:

For most plug-ins, it’s just impossible since the Mail extensions API is extremely limited. The plug-in developers I know filed enhancement requests right after WWDC 2021, but the API remains unchanged. Much of the API shipped in a totally broken state. Some of the bugs have since been fixed, but some remain. I wrote more about this here.


I worried about SpamSieve when I read that plug-ins were being discontinued. Now that I use my personal email more often, I rely on SpamSieve to catch spam … Drat. (An exclamation for polite company.)

(BTW, Thanks for writing such a useful application.)


SpamSieve will be fine, but we are having to do a lot of engineering to work around the things that extensions can’t do. And, it turns out, even the parts that extensions are supposed to be able to do don’t work reliably for all users all of the time, so a backup system that does things another way is necessary. So, at this point, the extension is a nice-to-have in that, when it works, it improve the user experience, but really we ended up rebuilding the app to require neither a plug-in nor an extension.


Ach. Shouldn’t have been necessary. Glad to hear SpamSieve will continue.


How will this affect SpamSieve? I rely on that to get rid of a lot of junk mail/spam that the lets through.

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The current version of SpamSieve will not work with macOS 14 (for those using Apple Mail), and there will be new version of SpamSieve available before Sonoma ships in the fall. More details here.


Thanks so much. This is really awesome. SpamSieve is wonderful.



Long time spamsieve users!! Great to hear it will survive this transition


Just another long-time SpamSieve user, echoing my appreciation of your continued hard work!

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Thank you so much!

I won’t install any MacOS that doesn’t include strong support for SpamSieve. It seems like Apple makes AppleMail a little bit worse with every version. I couldn’t face the daily onslaught of email without SpamSieve & a lot of mail rules & Smart mailboxes.

I filed feedback, hope it helps.


Michael, if you’re rewriting SpamSieve, does this provide an opportunity for SpamSieve to work with the ThunderBird mail app?

Where it’s going to hurt is losing Mail Act-on, part of smallcubed’s Mail Suite plugins. I must use that thing for nearly every message that comes in. They posted this message.

MailSuite will not work with Sonoma - macOS 14

Sonoma will be released later this fall without support for Mail plugins. Apple has permanently disabled the ability to load any Mail plugin in macOS 14. We are working on MailMaven - an email client to replace MailSuite - to be released later this year.We hope that existing customers will renew their Maintenance Plan and continue to support us with us on this new adventure.However …

  • We are no longer selling MailSuite to new customers through our site
  • If you are still interested purchasing MailSuite contact us directly at
  • An active Maintenance Plan for MailSuite will also work with MailMaven. and locks-in preferential pricing for MailMaven for as long as your Maintenance Plan remains active
  • To get more information go to
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It’s still on my list to add Thunderbird support, but this is not made any easier by rewriting the Apple Mail support. The Mail work has essentially postponed everything else I was working on.