1. Your email client (such as Netscape Communicator, Eudora, Outlook, or Outlook Express) initiates a TCP connection to the IP address of the POP/IMAP server that you have specified.

   NOTES: If your email client is set up to connect to a machine by hostname (instead of by IP address) here is where your first delay might be encountered, because the email client must resolve the name to it's IP address. Usually this will be answered immediately though, or not at all. So this might be the problem if you are unable to connect to the email server at all, but most likely is not the problem if you do connect to it eventually.

   When checking email that resides on the NetMAX, or using the SMTP server on your NetMAX, all of your email clients on the Internet should connect to a hostname that resolves to your NetMAX's external IP address, or you can specify the IP address instead of a hostname. All of your internal email clients (behind the same NAT that the email server is behind), should use a hostname that resolves to the internal IP address of the NetMAX, or you can specify the IP address instead of a hostname.

2. The sendmail email server on the NetMAX notes the IP address that the email client is connecting from.
3. The email server spends 30 seconds attempting a reverse domain name lookup to see what name that IP address reverse resolves too.

   NOTES: This is usually where the delay is caused, because when the NetMAX attempts to resolve that IP address to a name, it doesn't resolve. The main reasons why this happens are:

   1. The NetMAX's DNS server is not set to use the InterNIC. If you don't tell the NetMAX to use specific DNS servers for name resolution, you can set it to use the InterNIC by checking the box under Home|Network|DNS (provided that you have a NetMAX product that provides DNS services).
   2. The NetMAX's DNS resolver is not set to use the correct name servers. If your NetMAX is not a DNS server that is using the InterNIC, you must tell it what Domain Name Servers to use when it needs to resolve names. This is usually your ISP's nameservers. This is configured under Home|Network|DNS.
   3. The nameserver responsible (based on InterNIC records) for providing reverse resolution for that specific IP address is not answering requests at that time. This can be blamed on the ISP that owns that IP address space.
   4. The nameserver responsible (based on InterNIC records) for providing reverse resolution for that specific IP address doesn't exist, or isn't configured correctly. This can be blamed on the ISP that owns that IP address space.

      NOTES: But the NetMAX is responsible for this IP address (based on InterNIC records)? Then you don't have the latest version of the NetMAX (some earlier versions didn't set up reverse entries correctly), the NetMAX hasn't really been deligated responsiblity for reverse name resolution for that address space with InterNIC's records, or you haven't entered those IP addresses for the hosts into Home|Network|Machines under the appropriate domain.

      If the IP addresses are INTERNAL (private/non-routeable) IP addresses, and the NetMAX is responsible for reverse DNS, make sure that you are at the latest version, that you have a domain under Home|Network|Domains that contains the INTERNAL network, and that the IP addresses are entered with a hostname under Home|Network|Machines under that domain.

      What if some other machine is assigning my INTERNAL machines with IP addresses dynamically? Then that machine should do the reverse DNS for those IPs, because there's no way you're going to be able set up the NetMAX to do it, unless you want to get rid of that DHCP server and use the DHCP services on your NetMAX (if you have a NetMAX product that includes the DHCP services).

4. A connection is allowed after the reverse name lookup times out, or after a reply is successfully received.
5. The email client authenticates by providing it's username and password.
6. If authentication is successful, new email is downloaded (for POP), or new headers are downloaded (for IMAP), or the email is sent (if using SMTP and relaying is allowed from that IP or domain).

NOTES: Although this is now commonly referred to as "reverse DNS", there is no reverse mapping done, so the term is a misnomer. The resolution from IP address to name is handled in the same way as the resolution from name to IP address. The only difference is that the lookup is done on the IN-ADDR-ARPA infrastructure domain instead of the top level domain.
address-suppressed