Set default env values

env

 POSTGRES_PASSWORD=pg_password
 POSTGRES_DB=roundcube
 
-IMAP_HOST=tls://test-mx.rthoni.com
+IMAP_HOST=tls://mail1.example.com
 
-SMTP_HOST=tls://test-mx.rthoni.com
+SMTP_HOST=tls://mail1.example.com
 
-SIEVE_HOST=test-mx.rthoni.com
+SIEVE_HOST=mail1.example.com
 
-MAIL_USER_DB_HOST=test-mx.rthoni.com
+MAIL_USER_DB_HOST=mail1.example.com
 MAIL_USER_DB_USER=postfixadmin
 MAIL_USER_DB_PASSWORD=pg_password
 MAIL_USER_DB_DB=postfixadmin