Like @till wrote in https://www.howtoforge.com/community/threads/how-to-update-roundcube-to-1-4-1.83492/#post-397492
Do you really want to help ? Please also tell me how to allow ALL domain in server to access to that subdomain in format of mail.domain.com ?
I do not understand what that means. From what you wrote in your previous thread and this, I assume you want to have Roundcube at address mail.domain.com. This should just work. If you have several domains on that server and want to have an e-mail server for all of them, then you set the MX record for all those domains pointing to your e-mail server. If what you want is something else, please explain more.
I am not meaning mail server. I mean webmail url. There are many different domains on server. And I want them to access to webmail like http://mail.domain.com > domain.com is domain of each users'. I was doing it so in directadmin: https://help.directadmin.com/item.php?id=92
So the url should be different for each user, that is main.usera.com, mail.userb.com etc? That is problematic, what do plan to do to get ceritificates working for each of those domains? If you do not care about certificates, creating aliasdomain for each of user domains should work. Let's Encrypt allows 100 domains per certificate, so if you have less than that users even certificates should work.
I do not know a way in ISPconfig to do that for all domains (and I don't know, if that would be a clever feature to allow this). You can do it manually by using an alias domain. However, you have to do make an alias for each domain. On the pro site, that will also ensure your SSL certificate is valid for them. Apache itself supports wildcards in the alias domain, so you could add this to your vhost: Code: ServerAlias mail.* . But that will be overwritten by an ispconfig update and it will not include a valid LetsEncrypt certifcate.
You could make a server level config (not using ISPConfig's interface) for webmail.* to be served from the roundcube installation, but your users will get certificate errors when doing so as @Taleman said. I use a generic redirect for webmail.* to the main webmail url, which works fine on port 80 and also works on 443 with a certificate error on the first connect (users can bookmark the destinationfor the future). I also have a redirect for customer.com/webmail/ urls.
