archive emails in plain text file?


New Email
My email folder in appdata\thunderbird takes up about 4 Gb and is 'way past being conveniently archived. Thunderbird HELP seems not to address ways to save just-the-content of emails; there's always 40-60% additional unnecessary overhead in transmission protocols and whatever. Copying out the text for each email is impossibly time-consuming; isn't there some way to just save the meat of the emails in one giant (300 Mb?) text file and discard all the overhead?