What is realtime black list(rbls)
RBLs uses the dns protocol to query the well-known IP addresses which have been complaint to send junk e-mail. Using RBLs to prevent the junk e-mail is very useful. RBLs is different with Anti-Spam service: RBLs blocks the junk e-mail based on the IP addresses; Anti-Spam service block the junk e-mail based on the message content. Using RBLs can save the resources of mail server.
Where can I find RBLs servers?
EmailArchitect server has several rbls servers set by default, but you can find more rbls servers by the
following url:
http://www.robtex.com/rbl.html.
Trusted SPF/MX/A records
Because RBLs is not 100% correct, so using this option can prevent rbls block the normal message.
First of all, please learn more detail about Sender Policy Framework(SPF) by the following url:
http://spf.pobox.com/
http://www.microsoft.com/mscorp/safety/technologies/senderid/default.mspx
Although SPF is very good solution to prevent faked email sender,
but many domains haven't set the SPF record yet, so to check the MX/A record is very important to those domains.
e.g.
The email sender is: xxx@adminsystem.com and this email is from IP address: 210.17.235.64. By querying the dns server
of adminsystem.com, mail.adminsystem.com is the MX record of adminsystem.com and the IP address of "mail.adminsystem.com"
is "210.17.235.64", so there is enough reason to believe this email is not faked. And rbls will never block this IP address even
this IP address is list on the rbls servers.
Why RBLs blocks the local user to send email from dynamic IP addresses.
Now, more and more rbls servers list the dynamic IP addresses to prevent the bulk mailer to send junk e-mail. To let the local user to send email from dynamic IP addresses, the user must set the user authentication in e-mail client. If the user set the user authentication, the rbls will never block the connection.
See Also
Anti-Spam Service User Permissions SSL Configuration Domain Administration User Administration Incoming/outgoing Filters