Issue :
webmail.domain.tld does not work.
Fix :
1. Create an ‘A’ record for the sub-domain ‘webmail’ in the DNS zone file. It should look like :
domain.com. IN A XX.XX.XXX.XXX
localhost.domain.com. IN A 127.0.0.1
domain.com. IN MX 0 domain.com.
mail IN CNAME domain.com.
www IN CNAME domain.com.
ftp IN A XX.XX.XXX.XXX
cpanel IN XX.XX.XXX.XXX
whm IN A XX.XX.XXX.XXX
webmail IN A XX.XX.XXX.XXX
webdisk IN A XX.XX.XXX.XXX
2. Put the following code inside .htaccess in the sub-domain folder ( virtual sub-domain which doesn’t have an entry in httpd.conf
RewriteEngine on
RewriteCond %{HTTP_HOST} ^webmail.domain.com$ [OR]
RewriteCond %{HTTP_HOST} ^www.webmail.domain.com$
RewriteRule ^.*$ “http://domain.com/webmail” [R=301,L]