Are there plans to integrate a mail server in nextcloud? The user own his data so I think emails, too. In that proposal you could fork thunderbird and make it more slender and integrate the calendar function as default. The community needs a open source Microsoft Exchange and Outlook alternative imho.
I know at the moment you have many different things in your mind and important things to do, but it’s a recommendation for the future. 
I will strongly disagree with this.
Nextcloud needs to be Nextcloud. Including everything under the sun in a single product is always a horrible idea.
This product runs on platforms that already have perfectly workable mail servers available for them.
Additionally, this prodcut is a server side system. there is no reason to include a mail client in it.
I understand your point.
But I was not talking about all features under the sun just about a feature to support another data critical aspect of life. Maybe you don’t have to implement a own mail server but to improve the collaboration with an existing and break down possible barriers to integrate a specific mail server with nextcloud. It might be possible to view all mails from that mail server in your nextcloud UI or provide a graphical userinterface for that mail server. It’s just a generic idea which is still to discuss.
AFAIK there is a mail application for ownCloud. You don’t want to reimplement mail server especially in php web app. But mail client is there and AFAIK is being developed. Not as fancy as roundcube yet, but usable for basic stuff.
Current Owncloud has a promising - albeit beta - mail client with basic features and connectivity to popular mail server backend protocols like imap, pop, smtp. Given this app will be enhanced with better PGP/S-Mime integration, better calender integration, everything is planned already. Please have a look at the github discussions for the mail app about encryption; basically it is not desirable to have private keys on the cloud server, so we have a conceptual issue here. By the way, we have the same issue with contacts and calendars: no server side encryption possible.
I agree with JaredBusch entirely. A major part of the Linux/Unix philosophy is built around modularity. Bringing other core system functions into dependency on one application defeats this advantage, and we’re left with something very limited and cumbersome like MS Exchange, or Active Directory.
As Ben mentions, an app (client or management interface) that can integrate with an existing mail server would be a worthwhile approach.
Just to link to the app: https://github.com/nextcloud/mail
Also @ChristophWurst @Gomez and @jan are already here 
Actually, it’s both. It’s a file and “data” repo AND a GUI for both, but the current Mail app is a strange animal, because it manages data which sits outside of xyzCloud, so there is little reason to use it (just add contacts and calendars to a webmail instead), but it’s quite popular, so it’s here to stay and maybe one day it will store messages locally.
EDIT: It’s true that some other apps also manage files stored on proprietary clouds, so maybe it’s not such a strange concept to manage external data.
There are already great open source mail servers such as postfix or exim. Someone could provide a configuration sample for the mailserver together with a configuration interface plugin for owncloud (like postfixadmin or vexim).
I don’t think this is necessary because all these standard tools live on their own. They have their own documentation and their own prerequisites.
The mail App just uses standard protocols in a standard way (yes, the mail.app developers even documented what has to be altered for google and for exim), so I assume all is covered. *cloud and mail.app are independent of the mail tools.
If you look for an easy way of self-hosting a mail server then http://mailcow.email might be worth a look. Otherwise the Owncloud (now Nextcloud 
) mail app does the job for providing access to mailboxes IMO.
You should take a look at www.nethserver.org it has already integrated owncloud 9.x with one click install, making a module also for nextcloud would be very cool and interesting. NethServer’s straightforward to install and administrate, all through a modern webUI and based on CentOS
I’m happy to see this new project, I have waited for @jos’s next move for a while. Hi @jospoortvliet
Disclosure: I’m the NethServer community guy 
Beyond of what had be said, mail servers are too complex security-wise to be integrated into anything.
I think if Nextcloud find a way to make
to create a plugin for Nextcloud would be a lot of more interesting for everyone.
I’m in the ‘no’ camp here. Where Nextcloud’s functionality excels is its ability to integrate with other solutions and serve as a central command, per-se. It shouldn’t be a mail server; it should be able to talk to one, though. That’s why the plugin architecture is fantastic for this.
A mail server is something completely different. If you want to have a PHP-JS-Mail-server you can always look for or create an app for that. Until then, you should try your own mail server and you will soon realize why there are so few rolling their own.
Including a mail server is a whole nother ballgame.
The Mail Client on the other hand is being worked on AFAIK.
Ok let met change my suggestion to improve the mail server integration instead of create a Nextcloud mail server 
yeah, that’s what the Mail app is all about. And we want to deeply integrate it, like Calendar and Contacts.
Hi @alefattorini !!! Nice to see you here. Nethserver offers a great base for Nextcloud, once we have our first release (very, very soon!) we can sure see if we can promote the combination
Maybe @ChristophWurst and @Gomez of the Mail app want to state their plans here?
@xandcg just as a note – Protonmail claim they are open source but are not really, see https://twitter.com/jancborchardt/status/740219550805987332
This has been discussed before (can’t find the issue ATM) and I am still convinced that we should not re-invent the wheel. There is no sane reason to implement that ourselves if we can use a standardized protocol to communicate with existing, well tested, open source IMAP severs.
However, as mentioned, I’d welcome if someone documents how admins can set up and configure the Mail app and an external (but on their own servers) mail server
Mail app + a good turnkey mail server easy to administrate + nextcloud installation with 1 click = awesome!