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Win2k3 Cannot send mail on port 25

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by a former member

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I have a client's server running win2k3 and exchange 2003

Here is the problem
Messages are queuing up because the server can not send anything out on port 25.

server is internal and ports are forwared to internal address.

I can not telnet out of the server to any other mail server
results are as follows

could not open connection to the host, on port 25 : connection failed

The following things are known-:

Internal network SMTP works
Port 25 open and active on exchange.
Telnet from another machine to external mail server on port 25 works.
No firewall active
No Proxy anywhere on system
Even fails in when routed via DMZ mode
Port is open and receives connection from outside but will not respond.(wireshark see incoming connection on server interface)
Even with exchange turn off no external connection is possible.
DNS resolves correctly
Port Scans of ISP mail server cant see port 25
Portscan of this exchange server from outside shows open port.

I believe the fault is not the exchange but w2k3

3 replies

by Former member

Clarifications

by Former member

From the Tools menu select Accounts. The Internet Accounts box appears. Select the Mail tab. Your email account appears. Select the appropriate email account by clicking on its name and click the Properties button on the right. Then under the Outgoing Mail Server section check the box My server requires authentication. Do NOT check the box next to Log on using Secure Password Authentication.

Check connection to port 25

The standard port usually used for SMTP connection is port 25. Most often the reason for failed email sending is that your Internet service provider blocks this port. If is the case we recommend that you use the alternative port 2525 for your email SMTP connection.

Please post back if you have any more problems or questions.

by churdoo

What ISP provides your bandwidth, and are you using cable or DSL for bandwidth? Many cable/DSL bandwidth providers today block SMTP traffic beyond their network. For Exchange, oftentimes you have to specify a SMARTHOST in the Connector settings so that Exchange will relay outbound SMTP through your bandwidth provider's SMTP servers -- you sometimes also have to provide your ISP account credentials for SMTP AUTH connections. This is an anti-spam measure by design.

Post back for more info if you wish.

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