Configure a standalone W2K machine as SMTP server

[Carlos]

I have configured a standalone W2K server to act as a SMTP relay.


[CISCO PIX FIREWALL] ---------- [W2K standalone with SMTP]
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[EX 2000 SERVER]


Everything is working fine, however, it is very unstable. Sometime can relay
email and sometime fails. This problem apply to relay internal and external
email. When it fail to relay external email, I check the event log, it say
Internal DNS error.
There is a DNS server in the Internal network and the SMTP relay server
points to this internal DNS.

2 problems
----------------

1. In order to initiate a port 25 connection between the SMTP Relay and E2K,
I have to initiate a telnet port 25 from E2K to the Relay server. Once this
is done, the port 25 connection is okay. I have to do this, if I reboot the
Relay server.

2. The DNS is very unstable. The strange thing is nslookup works perfectly
fine. In the Relay server command prompt, I run nslookup and I can resolve
any IP domain name. But the SMTP service just failed and log in the event
Internal DNS error.
I manage to resolve the problem by reboot, restart service, do a couple of
nslookup, clear the 'Q' and many more things. And now the SMTP Internal DNS
error is back. Is it some sort of bug ?

3. I think the PIX rules is okay. I have checked everything. domain/udp
service is allowed, otherwise the nslookup will fail. port 25 is allowed
too, otherwise it would never be successfull before to relay email

Thanks

Carlos.

 

[Carlos]

Problem is solved. Article ID : 263237
Need to open port 53 in the firewall because SMTP service use TCP DNS
queries by default instead of UDP

Thanks