: By default, Gmail exports in MBOX format . To view this as text, you can open the resulting file in a text editor or use a converter to change MBOX to TXT.

: To generate a standard response "piece" within Gmail, enable Templates in your Gmail Advanced Settings to save and reuse drafted text. how do I save a gmail as text - Google Help

: Tools like Save Bulk Gmail Attachments on the Chrome Web Store can help automate the process of saving specific parts of your emails. Generating a Piece (Content Creation)