Access denied for user - error

When I add an entry in my guestbook, the persons receives a mail with a error message:

MySQL Error : Connection Error
Error Number: 1045 Access denied for user: 'rkvvdend_agbook2@localhost' (Using password: YES)
Date : Wed, January 21, 2004 06:54:04
IP : 145.221.92.40
Browser : Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 4.0)
Referer : http://www.rkvvdendungen.net:2082/frontend/babysim/cgi/advguest.html
PHP Version : 4.3.4
OS : Linux
Server : Apache/1.3.29 (Unix) mod_auth_passthrough/1.8 mod_bwprotect/0.2 mod_log_bytes/1.2 mod_bwlimited/1.4 PHP/4.3.4 FrontPage/5.0.2.2634 mod_ssl/2.8.16 OpenSSL/0.9.6b
Server Name : www.rkvvdendungen.net

Does this mean that my datbase can send mail or something else?

Please advise?

thanx Marty