Sending an email externally and waiting for a reply

[Ronen Fox]

Dear All,
 
On a CRM 3.0 system we have the following workflow scenario :
 
1. An email is sent to an external address
2. The system waits for a reply for this email
3. The reply is received and the workflow continues.
 
Can you please let me know what are the steps needed to accomplish this
scenario ?
 
Many thanks in advance for your help.
Best regards,
Ronen Fox