The domain and mails to it should be resolving from a server to access it through webmail link, below are the links to access:

Insecurely:

http://yourdomainname.com:2095/
http://yourdomainname.com/webmail
http://webmail.yourdomainname.com/

Securely:

https://yourdomainname.com:2096/
https://yourdomainname.com/webmail
https://webmail.yourdomainname.com/
The default port for webmail are 2095 and 2096. P vary when you use secure/insecure(with http/https)which will be 2096(secure) and 2095(insecure)

Replace “yourdomainname.com” with your actual domain name