text files vs mobi

Hi guys,

I've been experimenting with three ways of sending files to my kindle:

1. Creating an epub file, renaming it (not converting) as a text file, and emailing to kindle

2. Creating an epub file, converting to mobi in Calibre, emailing to kindle

3. Creating a mobi file in Calibre, emailing to kindle.

All options produce slightly different formats of the publication. If anything the text file looks best on a Kindle. Could anyone shine some light on whats going on, and which would produce better formatted publications?

Thanks