Thank-you for the help. I adjusted the configuration to reflect your suggestion. My mx record is set as mail.xeneum.com.
I also did a service postfix reload & service postfix restart and I'm still receiving the same error in roundcube.
Changed settings:
mydomain = xeneum.com
myhostname = mail.xeneum.com
I also did a service postfix reload & service postfix restart and I'm still receiving the same error in roundcube.
Changed settings:
mydomain = xeneum.com
myhostname = mail.xeneum.com