@oneitonitram
Oh, trust me I like Nextcloud and would use it. But from what I have run and seen with Nextcould it tends to have some challenges from how it seems to work. It also requires a beefy system to not be sluggish, also the email side of it is odd, it should have it’s own built in webclient, or at least make it easy to have others work with it - but I have not seen that (I am speaking of my experience with it - I don’t know if this is due to my installation only and configuration)
I am running Webtop 5 now. It does the job. But I have problems with calendar properly syncing to mine and others phones. The interface on it is ok, the admin on the backend is busy and kind akward. The Cloud/Files side (My resources) of it is also awkward and does not allow you to preview through a mouse over or clicking on documents (ex: pdf, jpg, png, tiff, doc, docx, xls, xlsx, and so on). There are other things about Webtop 5, but I will spare you it.
I use to run Citadel as my main email and it was a workhorse and just worked. The collaboration and groupware side of it is nice. The notes are a nice additive to the groupware and collaboration side. Same with the BBS / forums style, and it can also be access with text based terminal as tho you were connecting to a BBS as well.
I agree it could use a face lift (but I believe someone could fix that easy tho), infact it has customization docs for it here
Webcit:
https://www.citadel.org/customize_webcit.html
Example:
https://www.citadel.org/example1.html
UserList:
https://www.citadel.org/userlist.html
Room:
https://www.citadel.org/room.html
Login
https://www.citadel.org/login.html
RichEdit
https://www.citadel.org/richedit.html
also it could use a backup script and gui for it to be built in. (I believe this could also be added), it was easy enough to setup a backup that I didn’t worry about it not having it built in.
I would guess that that the vCard Support, CalDv, GroupDav and smartphone integration could be added as well.
But at the end of the day it just works and you know what your getting.