I'm looking for a software recommendation for an email server and webmail client to run on my own hardware.
I wasn't sure whether to post this in Server Fault, Web Applications, or Webmasters. I was told that for software recommendations, this stack is pretty much the only one -- here's hoping that you folks also do server-side software.
Currently my entire family is on GMail (a business account since before it was even called that), and we want to change away from it (for privacy reasons, but that's outside the scope of this question). As you know, one of the killer features of GMail is the use of "labels" instead of folders, and you can then apply any number of labels to a message.
Clearly, plain IMAP does not work with such a system; this doesn't really matter as long as there is a webmail client of sufficient quality. I would say that both Kolab and RoundCube probably meet the quality criteria -- but they follow "the IMAP model" where messages are in only one folder (although Kolab does have some tagging ability).
So, which alternatives are there for GMail's labels feature?
Bonus if it can run on a Synology NAS. Synology offers (at least) four different email servers, but they're all using the IMAP model.
Bonus if the mail server also supports calendaring. Kolab does, for instance, and I'd love to use it ... I'm just not ready to give up the multiple labels feature.