If this still fails it may be that the DNS server is faulty and is not responding or that a firewall or gateway is blocking TCP port 53 access. (some OS services only require UDP access which is why your firewall might be blocking TCP traffic on port 53) To test this telnet to your DNS server as per "telnet your.dns.server.ip 53". If this does not connect this is the problem. If this does connect then your DNS server is working fine.

DNS?  Do you have RBL's listed on your system that have gone away? Are your DNS servers overloaded and timing out?

Lyle

On 02/04/14 13:52, Charles Bender wrote:

Hey all,

My SMTP server seems to be taking an inordinate amount of time to respond to basic telnet requests. Some of them have taken over 30 seconds. This is causing an issue with inbound mail timing out.

 

Any ideas what could be causing this?

 

Total threads to the server are only 300 to 500 with a max of 213 SMTP.

 

I appreciate any thoughts. We are running 6.4a-1 on Windows.

 

Thanks,

Chuck