Word processing programs like MS Word, WordPerfect, OpenOffice Write, etc., format text very differently than Thunderbird does, which uses HTML. To make it simple, you can say that they speak different languages.

As you say, it normally takes some trickery to accomplish copying text from Word, pasting it into Thunderbird and getting the result you want. Given the difficulty in this, I personally recommend to people to either attach the Word document to the e-mail, or paste the text as "plain text", then modify it in Thunderbird to their heart's delight.

Of course, copying text from Microsoft Word and pasting it into Microsoft Outlook works great, because Microsoft designs those programs to work together, and you pay for them both.

Perhaps someone else will chime in here and provide different advice. Your question was 5 days old, though, so I figured I would give my opinion.

Thanks for answering and confirming that Thunderbird doesn't have a format option for double spacing. Thanks also for the info about Microsoft, but the changes I'd have to use Outlook make would be too extensive and expensive. The strange thing was that for several months, I could paste text in Word into my emails, and Thunderbird preserved the format. Then one day, out of the blue, it stopped.

Thanks for your reply. My problem, though, is that my version of Thunderboard doesn't seem to have any way to format double spacing.

I've recently seen several reports of Thunderbird's behaviour having changed in respect of pasted text.

Most complaints have been about additional blank lines being inserted. Using what is to hand here. TB52.1.1, Windows 10 Pro and Word 2010, I can't reproduce that. In fact, mine behaves more like yours; it removes empty space.

Line height is set by an html or css formatting statement. Thunderbird doesn't support this directly because such typographical control is really not appropriate in an email message. Email is not wysiwyg. But if other software places such a command then it will probably be honoured - bearing in mind that your correspondents' email client may not honour line spacing tags.

However, if text is copied into Thunderbird correctly from somewhere else, it ought to work. And if I copy single, one-and-a-half or double line spaced text from Libre Office Writer, it works just fine, and I can see the relevant coding in place and achieving the required effect.

In your case, I'd want to look over the underlying html/css code to see if a line height setting has actually been imported and applied to the text. Unfortunately, Microsoft do not see any obligation to comply with widely used standards, and their pasted text is a bloated mass of proprietary "mso" coding. It often has two versions of markup, depending on whether it is used in a Microsoft-compatible environment or not.

I would echo the advice given elsewhere; if the layout or design are a critical part of your message, send it as a word processor or pdf document as an attachment. The outcome with email is simply not predictable.

Give this a try and see if you like the results.

Top menu bar: Tools: Options: Composition section: General tab Or Menu button: Options: Options: Composition section: General tab

Select Use Paragraph format instead of Body Text by default.