How does the GFI MailEssentials URI DNS Blocklists filter work?

Answer

The GFI MailEssentials URI DNS Blocklist filter verifies that the Unified Resource Identifiers (URIs) found in the email are not known to be used in spam emails. The GFI MailEssentials URI DNS Blocklist filter performs DNS queries to the blocklists enabled in GFI MailEssentials, using the URIs found in the email message body.

Requirements:

All the queries done by this filter are done using DNS. By default, GFI MailEssentials will perform the DNS queries against the DNS server configured on the local machine. You can configure GFI MailEssentials perform such DNS queries using an alternate DNS server. This can be done as follows:

1. From the GFI MailEssentials configuration, expand the Anti-Spam node
2. Click Anti-Spam Settings
3. Click the DNS Server tab
4. Select Use the following DNS Server
5. Specify the DNS server to use
6. Click APPLY to save the changes

Important Note:

If the DNS server used for these queries is not configured correctly, the DNS queries performed by GFI MailEssentials may fail. This may cause timeouts in the queries performed by GFI MailEssentials, and may delay the delivery of the emails.