These restricitons are configurable on a per address basis.
Technical and Blocklist Restrictions
- Require Fully Qualified Envelope Sender
- Require Valid Envelope Sender Domain
- Require Valid HELO/EHLO Hostname Syntax
- Require Fully Qualified Domain Name in HELO/EHLO
- Require Client Reverse DNS
- Reject Forged Sender Addresses (yahoo.com, aol.com, hotmail.com, mail.com)
- Reject Forged HELO/EHLO In Your Domain(s).
- Greylist Invalid HELO/EHLO (Like <oemcomputer>, <Wxhtyd>, <mike>, etc.)
- Greylist Selected Senders (23,000 Free Email Domains, and problem TLDs like .ru, .pl, .biz)
- Greylist Selected IP Addresses (Dialup, No reverse DNS, Cable Systems, Problem IP Space)
- Reject Open Relays and Proxies (Local list plus list.dsbl.org, relays.ordb.org, opm.blitzed.org)
- Reject Persistent spam Senders (Local list plus sbl.spamhaus.org)
- Reject Virus Gone Crazy
- Reject Most Asian IP Addresses (IP space allocated to APNIC except for Australia, New Zealand, and Japan)
- Reject Dynamic IP Addresses (Local list plus Pan-Am Dynamic List and dul.dnsbl.sorbs.net)
- dul.dnsbl.sorbs.net
- list.dsbl.org
- relays.ordb.org
- dnsbl.sorbs.net
- sbl.spamhaus.org
- ipwhois.rfc-ignorant.org
- l1.spews.dnsbl.sorbs.net
- xbl.spamhaus.org