Hi Prem,
Adobe campaign generates a text version automatically if you left the text tab empty but it may not look beautiful by default.
You should use the Html to text button and format this nicely or create a separate text version.

Alternatively: if you are sending hundreds of email campaign then I would recommend using a custom HTML to text converter code. This code will convert HTML version to text like the campaign but with IntelliSense and nice formatting, This would be a custom implementation, need some work but good for large number of campaigns.
Regards,
Amit