If something goes wrong with your installation, there are a number of features that may help you to find what's at the root of the problem. The first place to check are smail's log files. They are kept in /var/spool/smail/log, and are named logfile and paniclog, respectively. The former lists all transactions, while the latter is only for error messages related to configuration errors and the like.
A typical entry in logfile looks like this:
This shows that a message from root to email@example.com has been properly delivered to host vstout over SMTP.
Messages smail could not deliver generate a similar entry in the log file, but with an error message instead of the delivered part:
The above error is typical for a situation in which smail properly recognizes that the message should be delivered to vstout but was not able to connect to the SMTP service on vstout. If this happens, you either have a configuration problem, or TCP support is missing from your smail binaries.
This problem is not as uncommon as one might think. There have been precompiled smail binaries around, even in some distributions, without support for TCP/IP networking. If this is the case for you, you have to compile smail yourself. Having installed smail, you can check if it has TCP networking support by telnetting to the SMTP port on your machine. A successful connect to the SMTP server is shown below (your input is marked like this):
If this test doesn't produce the SMTP banner (the line starting with the 220 code), first make sure that your configuration is really correct before you go through compiling smail yourself, which is described below.
If you encounter a problem with smail that you are unable to locate from the error message smail generates, you may want to turn on debugging messages. You can do this using the -d flag, optionally followed by a number specifying the level of verbosity (you may not have any space between the flag and the numerical argument). smail will then print a report of its operation to the screen, which may give you more hints about what is going wrong.
[Don't know,...Maybe people don't find this funny:] If nothing else helps, you may want to invoke smail in Rogue mode by giving the -bR option on the command line. The manpage says on this option: ``Enter the hostile domain of giant mail messages, and RFC standard scrolls. Attempt to make it down to protocol level 26 and back.'' Although this option won't solve your problems, it may provide you some comfort and consolation.