host name configuration error

Action: Follow the instructions that were provided for resolving this error message, 554 hostname... Local configuration error.

Technical Notes: This is an old sendmail message, which replaced I refuse to talk to myself and is now replaced by the Local configuration error message.

user unknown

Description: When you try to send mail to a user, the error Username... user unknown is displayed. The user is on the same system.

Action: Check for a typographical error in the entered email address. Otherwise, the user could be aliased to a nonexistent email address in /etc/mail/aliases or in the user's .mailrc file. Also, check for uppercase characters in the user name. Preferably, email addresses should not be case sensitive.

See Also: For additional information, refer to http://www.sendmail.org/faq/section4.html#4.17.