For example, a bold, red Times new Roman test is copied from word or an email, and be able to simply paste it into the editor and the stylings will not be removed from the text.
Ordered and unordered lists work, the other basic styling get lost during the pasting process.
Currently Rich Text preserves text formatting when copy/paste between Rich Text instances.
As for external sources, the pasted value is processed as a plain text due to limitations in how we can parse HTML and preserve the same structure in the pasted result (engine limited support for blocks and nesting, endless number of structure/style combinations to process, other limitations).
With all said, I’m afraid that we do not plan to add support for pasting formatted text from the external sources in recent future. We will definitely track the requests and revise what improvements can be done from our side, however for now the format saving support is limited to copy/paste between the Rich Text instances only.