Does anyone know how to disable emails from a server? I have had a report that someone is able to send spam emails from my server and I am at a lose on how to resolve the issue. This is a dedicated server so I do have full access.
Your server probably has been compromised if you have full access and are responsible for updates. The best thing is taking your server offline and contacting your support.
Block the SMTP port in your serve firewall and then find the root cause of the problem. You will get more information from your mail server logs. Please note that if you block SMTP port, it will block all emails from your server.
if you are using whm / cpanel you can set number of emails per hour to 1 this will prevent accounts from sending mass mails only 1 email will be allowed , second try disabling nobody from sending mail, third enable mail headers in apache to catch exact spammer
is he exploiting the script to send spam? if so harden the forms and php code or may be your mail account could be hacked. it happened to me once and i changed the password to a hard guess. Since then spam stopped.