$domain_name = $_SERVER['SERVER_NAME'];
$domain_name = str_replace('webmail.', '', $domain_name);
$rcmail_config['username_domain'] = $domain_name;
Thanks, that works perfectly. I also added these lines to
\program\include\rcmail_template.inc
so users can see their @domain.com after Username field in bold.
============================================
$domain_name = $_SERVER['SERVER_NAME'];
$domain_name = str_replace('webmail.', '', $domain_name);
[ .. skipped .. ]
$fields[user]@$domain_name | ============================================