I made a installation like yours, where I need to have two or more separate domains for mail address.
I don’t need to join to SMB or LDAP domains or to use it as file server so I use a dirty hack:
Suppose that mail domains are @aaaaa.nl and @bbbbb.nl
I installed my machine with local LDAP provider. The Domain I’ve assigned is @local.lan (yes, @local.lan)
For every user I create a firstname.lastname@example.org profile/login
Example: I have:
Mario Rossi (his email is email@example.com)
Piero Bianchi (his email is firstname.lastname@example.org)
Elisa Neri (her email is email@example.com)
Franca Rossi (her email is firstname.lastname@example.org)
I’ve created the following users:
In “Email” -> “Domains” I’ve created domain emails
That point to “this server”
In “Email addresses” -> Tab “Mail Aliases” I’ve assigned the correct email address to every user
email@example.com -> firstname.lastname@example.org
email@example.com -> firstname.lastname@example.org
email@example.com -> firstname.lastname@example.org
email@example.com -> firstname.lastname@example.org
In this way you don’t risk that someone who writes at the email@example.com (email that don’t have to exist), the mail is delivered.
You can login to POP3/IMAP/SMTP/Webtop/Roundcube either with name.surname or firstname.lastname@example.org (if you use activesync with webtop you must use email@example.com).
In this way you have user logins that aren’t bound directly to your email addresses.
Remember to put the host names of your domains in “DNS” -> “Server Alias”
If in your provider DNS you have registered mail.aaaaa.nl and mail.bbbbb.nl that points to pubic IP address of your server, you have to insert mail.aaaaa.nl and mail.bbbbb.nl in “DNS” -> “Server alias”.
Remember to create the correct entry of those hosts in your local DNS too.
If you want to use the webtop cloud to send/receive attachments, you should have a third “generic” domain/host (for example my.ddddd.nl) where download/upload links have to point.
Configure my.ddddd.nl in Nethserver as above for others domains, then digit the next commands in console:
config setprop webtop PublicUrl "http://my.ddddd.nl/webtop"
(http is correct, Nethserver will be redirect to https automatically)