On your information page about Gossamer Mail, you have the following requirements for the program to work..
1) Perl 5.004 or better
2) Mysql 3.21 or better
3) DBI and DBD::mysql perl modules installed

Is there any additional inforamtion that is required, such as, I assume you must have shell access...
Is there any requirement to make changes to the .conf files or the sendmail, .procmail, .foward, or virtuser tables??
The reason I ask is I purchased another product some time ago, but cannot use it due to making a change to the virtuser and sendmail that for some reason crashes the sendmail program on the server....
Thanks