When I try to login to RoundCube webmail by using the hostname (hostname.domain.com/webmail) it works fine but when I try to login to webmail using the domain name like domain.com/webmail or domain2.com/webmail it throws Login failed error. I have checked the login details and they are correct. Did I miss something here? I used auto-installation script to install ISPConfig Thank you
Do you use a different PHP version on the websites? It might be an incompatibility or missing PHP module then.