Apologies for butting in but presume you're talking cPanel WebMail (Horde etc), then port 2096 is for secure access so you would need
https://mydomain.tld:2096 (Alternatively
http://mydomain.tld:2095).
At the login prompt, enter the full email address
user@mydomain.tld or user+mydomain.tld along with the correct password. Works for me ...