Is the problem that the link in the E-mail event opens the form in edit mode?  If so you'll need to add rules to the smartform to make it readonly.   Something along the lines of:

1. initialize rule of the form
2. if the form parameter SerialNo has not been specified
3. then specify edit state for View and Form   (you can then make the controls readonly)

I believe this can be done with an email event if you build a Smartforms URL to perhaps a "ReadOnly" Form State that accepts some parameter for returning the Smartobject data, something like:

http://k2.denallix.com/Runtime/Runtime/Form/LeaveApproval/?_state=ReadOnly&LeaveRequestID=532

This "LeaveRequestID=532" and the configured rules will pull back the data

This "state=ReadOnly" will put it on that State that you have configured to be read-only