This setting might help you:

Go to Tools|Options|Composition|General and clear the checkbox "Use paragraph format…"

This modifies the behaviour of the return key. It might help with pasted text.

I should warn you that pasting text from Word will inflate your email documents, loading them up with pointless Word template material. Ctrl+shift+V or Edit|Paste without formatting in Thunderbird will strip out all the superfluous mso material.

Zenos, thanks, but the "Use paragraph format. . ." box has always been unchecked. Also, pasting Word doc text has never caused a problem before the Thunderbird update, and using the "past without formatting" option removes all the formatting I designed in Word and need (bold text; colored text, etc.). I tried the "Reset Defaults" button, but that just made all the text bold.

Mozilla needs to read these forum posts so they can learn of, and correct, errors in their updates or I, and others, will have to stop using Thunderbird.

But Thunderbird has its own controls for bold text, coloured text and much more. I don't think it should go out of its way to accomodate one particular word processor's foibles. Having said that, the paragraph format option in Thunderbird is pretty lame and near useless.

Microsoft's rich text gives me lots of problems. It is hard to control the format of a message that has been generated or previously mutilated by Word or Outlook. :-(

I do wonder why people use Word but not Outlook. These programs are natural partners and operate together well. You can configure Outlook to use Word as its editor component, so you wouldn't even need to do any copy-and-paste stuff.

Zenos, using Thuderbird's own controls for bold/colored/underline text defeats the entire purpose of having templates already created and ready to paste. The document templates I paste have 30 bold/colored/underlined text areas that would have to be recreated in Thunderbird every time I wanted to send an email, which would waste a lot of time.

I used to use Outlook, but when I updated my Windows software to 8.1, Outlook would place new mail in my inbox days late, and no solution was available or created by Microsoft. That's why I changed to Thunderbird, who merely needs to change back what the just changed in their update that is now causing the double line spacing.

It might take some time to recreate your Word templates as TB templates, but at least you would avoid the incompatibilities between the two programs.

Or indeed use the Stationery add-on.

I have just composed a fancy document, with assorted fonts, colours, a table and an image, with left, centered and full justification using Libre Office's Writer component. This pasted almost perfectly into Thunderbird, the only significant issue being that the picture was omitted. This suggests that given rationally formatted and standards-compliant content, Thunderbird handles it well. I am not too surprised at the picture misbehaving, given that a fundamental change in image handing in Thunderbird was recently announced. I am at a loss as to what recent changes in Thunderbird would have caused the problems you see.

All in all, pasting directly from Word is a less than ideal way to create an email message.

You may find that if you can get Word to save them as html documents, they may copy-and-paste more reliably, having lost the dreadful proprietary Microsoft formatting mark-up. .

Or, as sfhowes suggests, create templates in Thunderbird. Copy the content from Word, paste it into a new Thunderbird document. Fix it up (that may involve pasting as plain text then re-formatting using Thunderbird's tools) and then save the document as a Thunderbird template for re-use.

Zenos, I don't want to have to buy more software to make up for Mozilla's error they should fix, and I use dozens of templates in more than Thunderbird, so re-creating them all in Thunderbird templates won't always work. Pasting from Word is a popular method that any legitimate email software should accommodate. None of the Word file types were accepted by Thunderbird without the double line spacing problem. I don't want to have to waste time & effort creating/using work-a-rounds when Mozilla should fix the programming design error they mistakenly created and need to fix, but thanks for the offerings.

I can't reproduce that here. I'm using Thunderbird 52.1.1, Windows 10 and (reluctantly) Word 2010.

The html route works quite well too.

In both cases, I get a different issue; for me it discards empty lines and squashes the paragraphs together. No double spacing.

Thunderbird is Open Source software. Add-ons are free. No-one is suggesting that you spend any money.

I don't know what to say. Copy-and-pasting from templates just seems horribly wrong to me. Multiple steps to follow, in the right order, and you have to take care to copy and paste in a consistent manner. You don't know what elements of your mark-up may or may not be included. And there is the bloat and the proprietary MS coding. Ugh. Not how I'd do it, nor how I'd ask anyone else to do it.

Zenos and chris98597, may or may not be related, but tried reproducing https://support.mozilla.org/en-US/questions/1164680 by copying and pasting content from Textedit on MacOSx with and without list items. Didn't reproduce and I don't have Word. My point is: I'm wondering if something in the content that chris98597 is pasting (that is not in the content that Zenos is pasting) that is changing the format mode (like, lists, for example). I've been having problems with Paragraph mode getting turned on when I don't want it to (I actually never want Paragraph mode). I too have "Use Paragraph format instead of Body Text by default" turned off ever since https://support.mozilla.org/en-US/questions/1120056 . I swear I have seen Paragraph mode get turned on after pasting things into composition window, but unable to reproduce at the moment. I will certainly write back if I am able to reproduce it by pasting something. Good luck.

related, FWIW: https://support.mozilla.org/en-US/questions/1162683

Since you don't have Word, you won't be able to recreate the problem of Word text being double spaced when pasting the text in the body of a new Thunderbird email; however, Word is not the problem because Thunderbird had been allowing unaltered Word text for years until Thunderbird's last update, which created the problem. I have been using the same Word documents for years, so the problem is not with a problematic Word doc.

I read the link above when I first encountered the problem, but unfortunately, this link's solution involves an outdated version of Thunderbird that doesn't have the check box needed to try solving the problem that way.

chris98597 said

I read the link above when I first encountered the problem, but unfortunately, this link's solution involves an outdated version of Thunderbird that doesn't have the check box needed to try solving the problem that way.

Just to clarify for others, I think you are referring to this: https://support.mozilla.org/en-US/questions/1120056 The toggle at the time was called: "When using paragraph format, they enter key creates a new paragraph" and has been replaced with: "Use Paragraph format instead of Body Text by default" which is an improvement, but is unrelated to your problem.

chris98597 said

Thunderbird's last update, which created the problem. ... problem is not with a problematic Word doc.

I agree this is a problem in Thunderbird changing behavior. 1164680 is also a problem in Thunderbird changing behavior. At the risk of telling you something you already know/tried... I suggest providing steps to creating a simple Word document that when copied and pasted into Thunderbird shows the problem. Someone like Zenos (who actually has Word) may confirm and Mozilla will have an easily reproducible case.

Zenos,

I just got a new computer, Windows 10 and the latest Tbird. I've been using the older ones for years. I am a writer, graphic artist and poet and sometimes I need to paste something into an e-mail, often more convenient than an attachment.Now I have managed to get single line-space okay but it broke up a (copied and pasted from Word) poem into half-lines with 5 or six line spaces in places where there should have been none. I.e.. scrambled. Ugh. I could do all sorts of things with the previous version, greeting cards and so on by pasting in images and exploiting the fonts and colors in Tbird.