SMTP Connection Problems when delivering Email Notifications

When PaperCut NG tries to deliver email notifications and/or reports, the following error can occur when there are problems connecting to the SMTP server.

Note: The use of “smtp.server.name” in this article is a placeholder. Please use your SMTP server address when testing.

   Mail server connection failed; nested exception is javax.mail.MessagingException: 
Could not connect to SMTP host: smtp.server.name, port: 25; nested exception 
is: java.net.SocketException: Software caused connection abort: connect.

or

   Mail server connection failed; nested exception is javax.mail.MessagingException: 
Could not connect to SMTP host: smtp.server.name, port: 25; nested exception 
is: java.net.SocketException: Connection refused: connect.

When you receive this error, first check that the SMTP server is set correctly. If this is OK, then the most common causes of this error are:

1. That there is Antivirus software running on the PaperCut machine that does not allow outbound SMTP connections. This is common because many viruses and spyware use email to spread themselves. So either disable the virus-scan or add a exception/white-list that will allow PaperCut to make the connection.

2. There is a firewall that is stopping the connection. Make sure your firewalls allow this connection.

3. The SMTP server itself is not configured to allow connections from the PaperCut IP address.

One way to do a quick test to see if you can connect to the SMTP server from the PaperCut machine is to try the following from a command prompt:

   telnet smtp.server.name 25

If the screen goes black, then the connection has been established successfully. And this should mean that PaperCut will also be able to connect.