Microsoft KB Archive/170026

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SMTP Servers May Fail to Send/Receive Mail When on Same Server as Proxy Server

ID: Q170026

The information in this article applies to:

  • Microsoft Proxy Server version 1.0


SMTP servers (for example, Microsoft Exchange with the Internet Mail Connector (IMC)) may fail to send or receive mail when you set it up on the same computer with Microsoft Proxy Server.


Proxy Server acts as a firewall, filtering out all inbound traffic on the ports specified in the Winsock Proxy Server properties. Consequently, all traffic coming in on ports 25 and 110 is blocked.


It is possible to turn off Proxy's filtering of Ports 25 and 110.

WARNING: Disabling the Proxy Server's filtering of inbound traffic on any port dramatically increases the susceptibility of your network to outside attack as you are creating additional ways for intrusion.

To disable the filtering of Proxy server:

  1. Open the Winsock Proxy Properties page in Internet Service Manager (ISM).
  2. Click the Protocols tab.
  3. Click SMTP and remove it.
  4. Click POP3 and remove it.
  5. Click Apply, and click OK.
  6. Stop and restart your Proxy services and your SMTP service.
Keywords          : 
Version           : WINNT:1.0
Platform          : winnt 
Issue type        : kbprb 

Last Reviewed: August 9, 1999