So you want to write a KMail plugin?

Recently, I’ve been moving away from macOS to Linux, and have settled on using KDE Plasma as my desktop environment. For the most part I’ve been comfortable with the change, but it’s always the small things that get me. For example, the Mail app built into macOS provides an “Unsubscribe” button for emails.

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Apparently this is also supported in some webmail clients, but I’m not interested in accessing my email that way.[1] Unfortunately, I haven’t found an X11 or Wayland email client that supports this sort of functionality, so I decided to implement it myself. And anyway, I’m trying out Kontact for my mail at the moment, which supports plugins. So why not use this as an opportunity to build one?
↫ datagirl.xyz

Writing a Kmail plugin like this feels a bit like an arcane art, because the process is not documented as well as it could be, and I doubt that other than KDE developers themselves, very few people are interested in writing these kinds of plugins. In fact, I can’t find a single one listed on the KDE Store, and searching around I can’t find anything either, other than the ones that come with KDE. It seems like this particular plugin interface is designed more to make it easy for KDE developers to extend and alter Kmail than it is for third parties to do so – and that’s fine.

Still, this means that if some third party does want to write such a plugin, there’s some sleuthing and hacking to be done, and that’s exactly the process this article details. In the end, we end up with a working unsubscribe plugin, with the code on git so others can learn from it. While this may not interest a large number of people, it’s vital to have information like this out on the web for those precious few to find – so excellent work.