Reverse DNS Blacklisting allows DNS based blacklists to be used with MailEnable. This can help to control spam. It is possible to select which RBL blacklist providers to use, however, only the select providers that are needed as this feature has an impact on performance.
Enabled DNS Blacklists
This display window will show all the lists that have been enabled for the server. Including the MailEnable defaults and the personally created lists.
Add Button
To choose a blacklist select this button, select a list and click OK. The list will now be displayed in the “Current enabled DNS Blacklists” window on the DNS Blacklisting TAB.
Remove Button
To remove a list at any time select the blacklist in the 'Current enabled DNS Blacklists' window on the DNS Blacklisting TAB and select the Remove button.
Enable DNS Blacklisting
This enables or disables reverse DNS Blacklisting for the SMTP Connector.
Action when detected
The two actions here are;
Don’t accept the email - this will prevent connection by the remote server and respond accordingly. This is the best option for reducing server load.
Mark the message as spam - by adding a line to the header. If enabled the message will be delivered to the Junk E-mail folder within the email client.
Enable DNS Content Filtering
When enabled all messages will have their content scanned for links to web sites. When a link is found, then MailEnable will check the IP addresses of any URLs found to see whether they are contained in the selected blacklist.
Action when detected
The three actions here are;
Don’t accept the email - this will prevent connection by the remote server and respond accordingly. This is the best option for reducing server load.
Mark the message as spam - by adding a line to the email header indicating it is spam. This will allow locally delivered messages to be delivered to the Junk E-mail folder.
The Replace the link option will remove the failed link URL of the message and replace it with “Link is removed”.
Configure Blacklists Button
Opens a screen to allow blacklists to be created or added.
Lookup type
The lookup type that will be used for the blacklist.
Zone Server
The name of the DNS Zone or the IP Address of the DNS host that should be queried.
Record Type to check for
When the remote host or zone is queried, it may return one or more DNS Record types. Most implementations return an A record, but other implementations may return NS, PTR or MX records.
Response
The response that can be sent to the client when a message has been rejected.
Note: It is possible to configure a Whitelist that will override the reverse DNS blacklist.
Note: Reverse DNS blacklists affect the performance of incoming email. The reason for this is that for each inbound connection, MailEnable will perform a lookup in the remote DNS.
MailEnable provides a list of well-known Reverse DNS Blacklist providers. It is also possible to add your own blacklist provider by selecting the Configure... button.
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