Server software recommendation

Searching for a new mail/calendar/contacts setup for about 30 users.
eM-Client seems to be a rather nice client close to our wishlist.
What I’m searching for is a suitable server solution.
Our requirements/wishes are:

  • self hosted on linux, (so no GSuite, iCloud, O365,, Exchange, macOS Server)
  • if license is not renewed it has to keep the main functionality mail/calendar/contacts. (so no kerio connect as it dies the moment you don’t renew the license. Thats a toal no-go as it means your solution will die the moment the vendor drops the product or goes out of business!)
  • Multi-Domain, incl. shared calendars, shared contacts
  • customized automatic answers configurable via emClient (so no smartermail, MDaemon)
  • sync with mobile devices with push (so not caldav/carddav only as they are non-push)
  • open-source would be nice to have (free as in free speech, not free as in free beer! OS just helps to keep your data if the vendor drops the product or goes out of business.)

The only solution out of the officially compatible systems on the emClient that more or less meets that requirements is IceWarp (only failing at being open-source) but I never heard of them and have found no one around me using it.

So my question is: Is someone using a solution that meets that requirements and is willing to share some of their experiences?


The IceWarp Email Client is a rebranded eM Client with some additional features that are not available in eM Client. The server and client are very well integrated.

My opinion though: Exchange.


Hello Lukas,

We are happy for your interest in eM Client PRO.
For the eM Client - mail server compatibility, I’d recommend you checking our server guide at

If you’d have any questions or you’d need any help with the decision, please do not hesitate to contact me directly at

Russel Markosky
eM Client

which does not run on linux, so no.

Never heard of them - I will check them out. Thanks for that suggestion.

I already addressed every single one of those listed there in my initial request???


GFI Kerio Connect is also available on linux.

As already said in post 1: No interest at all for suicidal licencing…


Postfix SMTP + Dovecot IMAP/POP3 for Mail (Roundcube if webmail needed)

Nextcloud for CalDav, CardDav, Chat, File-Sharing, etc.

Dovecot is not fully compatible with eM Client. Among other things, public folders are not visible.