Webtop 5 with external users

Is it possible to create users within Webtop 5 without AD or LDAP?

AFAIK not on NethServer.

Well, you can create users belonging to a second domain.
But then the problem starts, if this domain is not hosted on NS.

Domain not reported in your first post. So please: would you describe a with more details your current setup? Feel free to use bogus/redacted data, but keep in mind that most of the forumers don’t know your environment…

OK, this is my setup:
Webtop 5 installed from NS Software Center;
NS is a mail gateway for domain A and host of Nextcloud and Webtop 5;
WT 5’s admin creates an additional domain B named like the domain of external users hosted with their email addresses on Strato;
problem: the locally created users cannot access their profile data, this menu section is greyed out. So, they cannot adjust their email imap and smtp data to their strato account.
The aim is to use WT 5 as a team groupware with all functions which WT 5 provides.
My alternative attempt to do this with a circle within Nextcloud has the drawback that Nextcloud users of this circle are not visible in the contacts list. The members of the circle cannot see the contact data of any other member. Some Nextcloud developers discuss this feature since years without any turnout so far.

Hard stop here.
AFAIK aAs default and as current support in Nethserver, Webtop 5 is considered as email/workgroup client for only the local email server. So as default, your current scenario seems not supported by nethserver.
Could you achieve that anyway with custom configuration? Currently I don’t know.
Can Webtop 5 do more than that? I don’t know, but I believe so.

Fair and square, however AFAIK not possible with the standards of NethServer.

Sorry for that, but here is still NextCloud and Webtop on Nethserver.
You can still look for shared solutions and experiences on these modules; you can also use your current nethserver (or another) installation as a local proxy for Strato mail services but it is a specific path to go for, with disadvantages, limitations and some other quirks.
Looking for experiences in other place is something i’d suggest you, at least for NextCloud, but remember that mostly will be nextcloud “on something else” than NethServer; I currently don’t know if there’s any public forum for Webtop in any form or access.

Now, all written above it’s purely my knowledge/experience, and I am simply a person, not the source of the truth. It’s perfecly fine to disregard that and look for more options. The only thing I suggest you is to report here the outcome (whenever it is) for your scenario. Might be useful for other people.

Maybe somebody from the NS developers can tell if Webtop 5 can be installed on NS independantly, i.e. without having the configuration bundled with NS.
Webtop 5 can be downloaded here:

But I have no idea how to compile this.