Hi
Wouldn't it be easier just to use a trigger/scheduled job to send an email to the client directly from the server?
Here's a great article describing how to send mails:
http://articles.techrepublic.com.com/5100-10878_11-6164310.html
If you're willing to throw money at it, I've used 3 products to send/receive notifications to and from clients/suppliers depending on their requirement:
KnowledgeSync (http://www.vineyardsoft.com/)
Network Automations Automate7 (www.networkautomation.com/automate/7/)
CoreTalk (South African SMS/Text message based CRM application with excellent database integration http://www.coretalkgroup.com/)