We have this program at school, which keeps track of everything. Schedules, pupils, teachers, courses etc. It has a web interface and a desktop client program interface. The web interface is run on one Linux server, the actual database program is run on another Linux server. The latter one does all the heavy stuff, the web interface only, well, the web interface. So when certain action in the web interface causes e-mail notifications to be sent, the other program does the SMTP stuff. Then we have the e-mail server on yet another server machine.

The database program fails to send e-mail. It seems to fail to make a connection to the e-mail server, as if the firewall would block it. But when I send e-mail from the terminal of the Linux in concern, using telnet and HELO, the e-mail goes through the firewall. I fail to locate where the problem is. I'm responsible for the database program installation, but not for the Linux server. The database provider blames on the connections to the SMTP server. The guys responsible for the Linux server (and its connections to the TCP/IP world) blame on the settings in the database program.

After succeeding in sending e-mail from the Linux terminal, I begin to suspect the database program. Could I have missed something?

There is usually a setting in the web server, such as php.ini, that directs the mail to the sendmail program or whichever SMTP service you're using. You may want to investigate that area [edit: by that area, I mean of your dbms software ].

I guess it's more of a custom thing, especially when e-mail is concerned. Desktop computers in our intranet run client programs (Windows), which contact to this main program, which runs on a Linux server. I have no idea of how the actual datafiles are organized, but that is probably not relevant. The main program provides data and whatnot to the client programs that turn it into a Windows interface. The main program also has a data connection to the web interface server program.

The main program, which runs as a process on the Linux server, is the one connecting to the SMTP server. The firewall of the Linux server is open, enabling sending e-mail from the command line (telnet, HELO). The settings inside the main program have right IP and port for the SMTP, right sender and receiver data etc. Still the main program reports a "Connection failure".

I start telnet in the Linux terminal. telnet has its own command line interface. Here: http://www.debianhelp.co.uk/mail.htm

The "real thing", the main program, asks for usual stuff in the settings. SMTP IP and port, sender and receiver e-mail addresses etc. That's all I know.

No need for a service. You could try a client like msmtp as a second verification that things are working, but that should be functionally equivalent to a telnet session. Won't hurt though. If that fails that's a good hint. Other things I can think of:

• Perhaps the software thinks it should connect using a secure (SSL|TLS) connection whereas the server doesn't support it [on that port].

• Perhaps there is an extra layer of security on the system, such as SELinux, and the process has the wrong context for the work that it's trying to do.