Hey Scott,
To do what you asked about earlier, I would have your clients set up in a table with a record for each client having their e-mail address and the name of the file to attach.
You can then do a query like this:
<cfquery name="q1" datasource="myDS">
select * from clientTable
</cfquery>
You can then just use the cfmail tag like this to send an e-mail and attach their file.
<cfmail
query="q1"
mimeattach=#q1.clientFile#
to=#q1.clientEmail#
from="billing@ourdomain.com"
subject="Your invoice"
>Here is your invoice......
</cfmail>
If you needed to attach more than one file, I would use the <cfmailparam> tags as Sylvano suggests.
Hope this helps,
GJ