Re: Re: Thunderbird – How do I send plain text and html emails permanently? Home › Forums › Email Tips › Thunderbird – How do I send plain text and html emails permanently? › Re: Re: Thunderbird – How do I send plain text and html emails permanently? June 15, 2009 at 12:03 am #32061 MitzKeymaster Go to Tools>Options>Composition and click the Send Options button.Expand the Text Format menu and choose behaviour. Mitz from Tips4pc