Matthew 5:17-18 (KJV)
  17 Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil. 18 For verily I say unto you, Till heaven and earth pass, one jot or one tittle shall in no wise pass from the law, till all be fulfilled.


As I understand it, the Law of Moses is fulfilled in Christ. We don't make sacrifices anymore, and many other of the finer points in the Pentateuch are no longer preached.

Yet, I still see people reference these books for doctrine (for example the 10 Commandments).

How much of the Law of Moses still applies?


Question: Is it better to put "Preview" on an iFrame with a specific height or just show it in full?
Answer: I agree with Michael regarding his suggestion and about iFrames. From the original question, I recommend going with option 2.  Adding a sticky bar across either the top or the bottom of the browser in a contrasting colour would help to modernize the experience. 

Similar to Themeforest:
http://themeforest.net/item/micron-retina-responsive-multipurpose-theme/full_screen_preview/6949939

See how they have their main sell bar at the top but it doesn't impede on the experience of the preview?

In terms of specifically email, I believe MailRox does the same thing. The preview is within the screen with the tools at the top.



Having 1 set of scrollbars (specifically the browser scrollbars) is more ideal.