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Can you log what DNS queries are genereated during such a POP3 session?<br />
I.e. either turn on logging at your local nameservers during a &quot;slow&quot; session or tcpdump traffic to 8.8.8.8 during a &quot;fast&quot; session?
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Can you log what DNS queries are genereated during such a POP3 session?
I.e. either turn on logging at your local nameservers during a "slow" session or tcpdump traffic to 8.8.8.8 during a "fast" session?

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There is qmail installed. POP3 connection is very slow or fails if my local namerservers are specified in /etc/resolv.conf. As soon as I change content of /etc/resolv.conf to some external nameservers (i.e. 8.8.8.8), POP3 connection starts working just fine.<br />
My local name servers are resolving domains fine, including reverse records. No delays noticed.
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There is qmail installed. POP3 connection is very slow or fails if my local namerservers are specified in /etc/resolv.conf. As soon as I change content of /etc/resolv.conf to some external nameservers (i.e. 8.8.8.8), POP3 connection starts working just fine.
My local name servers are resolving domains fine, including reverse records. No delays noticed.

POP3 connection is very slow or fails

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.

Email Servers

The Domain Name System (DNS) is a hierarchical, globally distributed system responsible for associating the name of a computer, service or other resource into an IP address for connecting to the Internet or a private network. Most prominently, it translates domain names to the numerical IP addresses needed for the purpose of computer services and devices worldwide.