Mail Server Security

We are using icewarp 10.1.3 just curious to know what steps you would take to make it secure against Open relay/abuse/spam etc ?
 
Any suggestion would be much appreciated.

Here are few steps which you can take to secure the mail server setting
1. Reject if domain is not local and not authorize
2. Enabled pop before smtp
3. remvoe public ip from trusted ips and hosts.
4. Enable  DNSBL blackhole list
5. Enable reject if originator domain doesnot exit

6. enable require helo/ehlo 
7. Add SPF record

Check the icewarp kb for more info http://esupport.icewarp.com/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=88