Hello all,

I finally found the answer to my dilemma. Opera Menu>Preferences>Privacy & Security Handlers (scroll to Bottom)

Allow sites to ask to become default handlers for protocols (recommended)

Do not allow any site to handle protocols

Select Mange Handlers... Button

Protocol Handlers>webcal

Cleared in my case 'mail.Comcast.com'

Fixed

When Clicking on an email address on a webpage, any-page!

Apple Mail redirect gets reset to Opera for Macintosh and (keeps changing settings in Apple Mail Settings back to Opera each time changed back).

Which in turn lunches "Xfinity.com" Login webpage in Opera.

Version information
Version: 38.0.2220.29 - Opera is up to date
Update stream: Stable
System: Mac OS X 10.9.5 64-bit