Re: using IIS as SMTP relay, now POP users cannot authenticate

Hi, found the issue.

The server in the DMZ acting as a relay is not a member of the domain, and
had numerous SMTP authentication errors in the even logs.

Is there a way around this?


"Ahmed Ashour" <AhmedAshour@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:C6C8733B-AFDF-48FF-80ED-0653FABA0DA8@xxxxxxxxxxxxxxxx


"Andrew Story" wrote:

Hi NG,

Our exchange server was configured to send mail to our ISP as a smart
host.
I have just modified our exchange server to use an IIS server we have in
our
DMZ to act as a smart host, our firewall (incoming) SMTP rule was also
changed to forward mail to our new IIS server in the DMZ, all looked
well.

But, our POP3 users (external) cannot autherticate anymore?

Any ideas why this would be?


Reply:
POP3 users use SMTP for authentication so if the ports are not opened in
both ways in the two firewalls (the front firewall and the back firewall)
authentication will fail.
Try to ask them to telnet the SMTP server in the DMZ in port 25
Also try to telnet the SMTP server in your internal network.
Check if they tick my outgoing server requires authentication option in
their outlook profile.
Monitor the traffic in the both firewalls to see what type of traffic pass
and what fail?





.

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