Confidential information.

Can you answer this question please, or point me in the direction where I can find out.
When an email is sent from a form on our secure ASP.net website and a directory is protected by a Verisign type certificate.
How secure is that email when it arrives at the webmaster's email address and also when it arrives in the designated email addresses specified on the form:
1. The person filling in the forms email address. 
2. A  email address in the code of the form that is directed from the webmaster.
We want to receive emails that contain confidential information.
Can you advise please.
Thanks
DaveMon

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