Nextcloud Mail introduces Machine Learning for Priority Inbox while protecting your privacy

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Flooded by email? Think the only solution is to give all your data to Google or Microsoft because they have smart inboxes that help you handle the flood of mails? We have good news for you!

Today Nextcloud Mail introduces a Priority Inbox. It uses machine learning to classify important messages as such and shows your mail sorted into the categories important, favorites and others. And the best part: unlike approaches employed by public cloud services, the learning happens locally and only uses the data from individual users to protect your privacy.

John Oliver facial recognition trailer image

Busy? Machine learning to the rescue

Machine learning is all the rage in Silicon Valley. And of course they are vacuuming up massive amounts of data, often in schemes that are downright unethical. Just watch the latest item on facial recognition by John Oliver to get a taste.

For us at Nextcloud, we know how important it is to get at your data quickly and efficiently. That is why Nextcloud shows you relevant files on top of your file view when you log in, and why we show contacts you frequently share with in the share dialog. We also use machine learning for security, training a neural network on your logins so we can detect when something out of the ordinary happens and warn you that somebody might be trying to hack your account. But this machine learning happens entirely local, on your server, using your data. Protecting your privacy. And it works well, as the millions of users of Nextcloud Hub can attest to.

graph of suspicious login training results

Introducing the Priority Inbox: learning to get better

Today, we’re proud to announce another use of machine learning in Nextcloud with the Priority Inbox in Nextcloud Mail. The Priority inbox separates messages into important, favorite and other messages. This gives you a more efficient way to sort and find what matters in your inbox, even when you are flooded with large amounts of email.

The priority inbox builds on the recent introduction of a message cache, improving performance of the Mail app for users especially on slow or very basic IMAP servers. A machine learning model is trained on your emails, looking at whom you email with frequently and other factors. We’ve been testing the model for a while now and it works quite well. But we will also improve it in the future, adding more factors and tuning the existing ones. More importantly, the model learns from manual classification of emails as important by you, the user. This means that the accuracy of the Priority Inbox gets better over time, as you use it and correct its decisions!

This release of Mail also introduces multi-select, improved search and other user interface and interaction changes. It is already available in the app store and you can get it right now!

screenshot of the priority inbox

Above you can see a screenshot of the priority inbox in action.

Of course, we will expand our use of machine learning in Nextcloud even further and if you’re interested in the subject and like to employ it to help millions of users get their work done every day, you can get involved!


I think what guzzisti is trying to tell us with his somewhat crude language is that the mail app deserves attention in many other places.
The mail app is far from being a real full featured mail client.
Dragn drop, performance, better integration etc.
There are so many other things I would think of before I start implementing an machine learning.
This is where the community is needed to push the open source project in a better direction.

Do what makes sense, not what is fun!


Clearly you have a distorted view of what this release was about. You could simply check the changelog for all the changes that went into v1.4 but hey, why not first rant on a forum, right?

Also has all the “other places” and it shouldn’t be hard to discover that we are working on many of the basics. Most people that are involved in the community know that and they appreciate the progress.

What is the big deal with working on the basic features and things that greatly improve the usefulness of this app?


I don’t have a distorted picture here.
This article is about machine learning.
Just casually about the other new features.
And I left out my opinion on that one.
If (my) opinion is presented as a rant, I don’t understand the sense behind a forum.
The choice of words of the first post were of course not correct.

I always read the change log and the roadmap in git with interest.
Even as a full-time developer I know that nothing is that simple anymore and that everything is a moving target.
But when I see that they have been working on basic features like changing the sort order #679 for over 3 years I wonder if the focus is not wrong.

I personally and customers who use it professionally (small business) just don’t understand why such things still don’t work.
There is a danger that these people will switch to other paid products.

I see a lot of potential in NC but there is still a lot to do.
So please do not feel personally offended.
All of this creates a community, not a single person.



To shed more light on this, please note that the app is not new. It’s been worked on by people of the community for a long time, even when our software had another name. As it happened, I got hired by Nextcloud GmbH but the app remained more of a side project. Only recently this has become a priority for us as more customers want fully integrated groupware in Nextcloud. I hope that explains why some of the feature requests are old.

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Thanks , @ChristophWurst that helps explain where we are, I think you are right that there is a clear community and customer pull to improve the app (sadly I could only but test) and it looks as though there is renewed emphasis with you joining Nextcloud.

For those that need improved features would it be worth refreshing a schedule or refreshing feature requests in someway to give a better view of demand and potential fixes?

I’d say that depends on the individual requests. Some have a lot of details and are well described with the acceptance criteria, others are just sparse phrases that leave a lot of freedom. With an :+1: you can best express your demand of something. Then we can sort them like and see which features got the most thumbs up.

Right now the roadmap is mostly influenced by what Nextcloud GmbH’s customers would like to see, though, and what community people implement off-schedule. So it’s quite a mix and we’re not too strict with our roadmap. This is just a rough overview of the things that we plan to certainly have vs the things that are nice to have.


Christoph, I need to say that the mail app is a great feature for Nextcloud. I really look forward to use Nextcloud Mail as my main mailclient for my company. The deep integration in Nextcloud is already impressive. Of course it’s not yet that mailclient which could be used in a normal business environment (to me, folder management + drag and drop would be essential).

So: Thanks for putting all the effort into the mail App.

btw: Any plans yet, for a Android app?


out of my own experience with nextcloud mail in a start-up environment:
First things first: the integrated approach including an email client is a big asset of nextcloud overall!

Now reality kicks in, just two very small examples:

  1. most users have a hard time to enter mail adddress into a new email, as the way of getting them into the address field is not intuitive at all. There were situations where people simply didn’t understand why the smtp address is shown, but somehow they cannot send the mail.
  2. If the distribution list is more than 3-4 recepients it is impossible to see it completely, at least we didn’t find a way of doing it. So they don’t know who got the email they are reading.

Bottom line is: I had to configure thunderbird for each of them as they didn’t feel comfortable to handle mails in an “in control” way in the mail app of nextcloud.

With that perpective I can related a bit to what stoamandl1 is trying to say here. For me it is a bit sad to lose some users to email clients outside of nextcloud. But how to argue with them?

I guess this is about

I’ve not seen this personally but I think I know why this happens. Guess we should just wrap the line or similar. Mind opening an issue?

That is sad. But developing a decent mail app is an iterative and collaborative process. Report the issues you’ve found, help testing or even submit patches. You can also get a Nextcloud subscription to fund some of the development.

Mail is filling up my nextcloud.log. Can you do something to prevent this? Deactivating the app cannot make sense.

See Log entry "not enough messages to train a classifier".

This is off topic.

I’m closing this topic as the sole purpose was the release announcement. For any other discussion start a new topic and report bugs via Github.