I installed exchange 2003 on this small business server about 4 months ago. After configuring it with the basics (forwarded ports, installed sp2 for exchange, setup imf, and verified business IP with a dns reverse showing the domain name to validate it to other mail servers that require the ptr) I still have one problem. The people who maintain and build our website use mozilla thunderbird as their email client. When they attempt to email known valid email addresses within my domain they get an error:
"An error occured while sending the mail. The mail server responded: sorry, no mailbox here by that name (5.1.1 - chkuser). Please verify that your email address is correct in your Mail preferences and try again."
Anyone know if it's their mail client or something with the exchange server that needs to be changed? I've never used thunderbird.