We @openvz.org reject emails
- coming from servers which does not understand "temporary failure" SMTP codes and does not resend emails
- coming from non-existent senders (i.e., back sender validity verification is performed)
- listed in some RDNSBL lists (see below)
dnsbl
We use the following realtime DNS blacklists:
- bl.spamcop.net (see http://www.spamcop.net/)
- sbl.spamhaus.org (see http://www.spamhaus.org/)
- cbl.abuseat.org (http://www.cbl.abuseat.org/)
If your mail server address is in that lists, your mails will be rejected.