GFI MailEssentials is processing emails very slowly

The information in this article applies to:

  • GFI MailEssentials for Exchange/SMTP 10
  • GFI MailEssentials for Exchange/SMTP 11
  • GFI MailEssentials for Exchange/SMTP 12
  • GFI MailEssentials for Exchange/SMTP 14
  • GFI MailEssentials for Exchange/SMTP 7
  • GFI MailEssentials for Exchange/SMTP 8
  • GFI MailEssentials for Exchange/SMTP 9

Article ID: KBID001770

Query keywords: dns, slow

Issue Encountered:

GFI MailEssentials is processing emails slowly. This eventually causes a queue of emails to be built up, especially in installations with large email flow. When GFI MailEssentials is installed on the same machine as Microsoft Exchange server, emails appear to stop in the Exchange Pre-submission Queue.


More Information

This issue may be seen when DNS problems occur in the network and one of the following options are enabled:

  • DNS Blacklists (GFI MailEssentials configuration -> 'Anti-Spam' -> 'DNS Blacklists').
  • Verify if sender domain is valid (GFI MailEssentials configuration -> 'Anti-Spam' -> 'Header Checking' -> 'General' tab -> Check if sender domain is valid (performs reverse DNS lookup on MIME FROM)).
  • Sender Policy Framework (GFI MailEssentials configuration -> 'Anti-Spam' -> 'Sender Policy Framework'). 
  • Spam URI Realtime Blacklist (GFI MailEssentials configuration -> Anti-Spam -> Spam URI Realtime Blacklist). This feature is only available in GFI MailEssentials 11 and higher.

All the above mentioned features rely on the DNS server specified in the GFI MailEssentials configuration -> right click on Anti-Spam -> Properties -> DNS Server tab. If DNS is not working correctly, the DNS lookups made by the mentioned features will timeout.


Solution:

Starting from GFI MailEssentials 11, each of the mentioned checks has a ‘Test’ button. The ‘Test’ button should be used to check the connection to the DNS server.

If the ‘Test’ returns failures, this will indicate issues with the connection to the DNS server and therefore any DNS checks should be temporarily disabled from within GFI MailEssentials, until all DNS related issues are resolved.


Notes:

The following are some tips on how to troubleshoot DNS issues:

  • Use ‘nslookup’ as follows to ensure that the default DNS server is correct.
    1. Open Command Prompt
    2. Type ‘nslookup’ and press enter
    3. Type a domain that you would like to query (for example: gfi.com), and ensure that there are no delays in the result.
       
  • Check the Microsoft Event Viewer to see whether the Microsoft Event logs contain any DNS related errors.
     
  • Check the Directory Service logs on the GFI MailEssentials machine and the DNS logs on the DNS server.
     
  • Use DC Diagnosis tool, ‘dcdiag /v’ to diagnose any errors.