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I send email to people whose mailers don't show PNG images correctly, so it seems to them that I sent no images inline at all. In thunderbird, I can't see any options to paste inline images as GIF or JPG instead of PNG. Is there a way to do this?

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up vote 3 down vote accepted

Look at the Pasting of Images from the Clipboard article on the Mozilla Knowledge Base.

There is a described parameter clipboard.paste_image_type to switch between PNG and JPG.

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In Thunderbird 3, Go to Tools -> Options -> Advanced (tab) -> Click on "Config Edtor" -> search for "paste", and select the clipboard.paste_image_type option, changing it to 1 – K Robinson Jun 14 '10 at 16:02

Well, how exactly do you "paste inline images"? If you paste an image file (e.g. drag&drop from a file manager), TB will include it as-is, i.e. JPEG as JPEG, PNG as PNG etc.

Do you want TB to convert PNG images to JPEG/GIF on the fly? Or are you pasting screen shots? On what operating system?


I just tested this: Thunderbird will include images in the system clipboard in whatever file format they are, just like images from image files. So the file format depends in TB on which file format the screenshot software used.

If you use Windows's built-in screenshot function (PrtScr/Alt-PrtScr), it will use BMP (up to XP) or JPEG (Vista/Win7). If you use another software like Snagit, you need to configure the file format there ("output file format" or similar).

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I am pasting screenshots on MS Windows XP. Usually, I have copied the image to the clipboard from SnagIt (a commercial screenshot application--a trial version lasts for 1 month). – K Robinson Mar 4 '10 at 7:08

When I copy an image from say, Photoshop, and paste it into my message that I'm composing, it converts the image to a PNG.
This is very annoying because some cellphones do not display PNGs, and there isn't any indication that there was an image supposed to be there.
Additionally, the image is not attached to the email, so the receiver is baffled as to what you're talking about.

Thunderbird has, since it's inception, never dealt with pasting inline images correctly.

This is how you do it: Windows XP running Thunderbird 3

C:\Program Files\Mozilla Thunderbird\defaults\pref

  1. Right click composer.js, choose Edit (or open it in Notepad).
  2. Go to the bottom of the file and find clipboard.paste_image_type

    // Pasting images from the clipboard, order of encoding preference:
    pref("clipboard.paste_image_type", 1);

  3. Replace the 1 in pref("clipboard.paste_image_type", 1); with a 0.
  4. Save the file, restart Thunderbird.
  5. Thats it.

Now when you paste your copied image into the email it works! You will get something like mozscreenshot_1.jpg at quality 95 embedded in your email.

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You do not need to edit the js file. In Thunderbird 3, Go to Tools -> Options -> Advanced (tab) -> Click on "Config Edtor" -> search for "paste", and select the clipboard.paste_image_type option, changing it to 1. By the way, this was already covered in the first answer I accepted--if you follow the link and look at the 4th bullet point. Still, this answer makes it more explicit. – K Robinson Jun 14 '10 at 16:02

Working with Thunderbird v24.3 in Windows 7, the only way I found to get the image truly imbedded (i.e. base64) was to drag and drop from the file manager(Explorer) into a newly composed HTML email. What I found online instructed me to use "Insert->Image", however all of my attempts to insert images via the menu option resulted in a reference to the image file on the hard drive (when the reference entry was properly formatted). Although Thunderbird embedded the image when sending, I wanted it entirely embedded within the HTML with base64. This resulted in no image files required on the hard drive, just the resulting HTML file. Your results may vary...

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