Error message for SMTP portion of e-mail config is no help

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Get this information from the PHP diagnostic (in the configuration wizard).
Gallery URL (optional but very useful): n/a
Gallery version: 2.2.3
Apache version: n/a
PHP version (don't just say PHP 4, please): n/a
Graphics Toolkit: n/a
Operating system: n/a
Web browser/version (if applicable): n/a

I tried to configure the e-mail in set-up. It has 4 blanks. I have no CLUE what to put in the fourth one. The error message just sounds like a 2-year-old: "no". It would help, since the codex says nothing on the subject that I was able to find, if the error message gave a clue (or the original screen gave a hint).