So, all of your pictures are natively in portrait mode? You never take landscapes?

I'm struggling with your assertion that it always rotates pictures. Please do try with a picture that is landscape orientation.

My usual answer is that actually, your problem is that Thunderbird has not rotated your pictures. It falls to act on embedded data included with some images that tells the displaying program how to rotate the image. It just shows the image with the pixel (0,0) at the top left, ignoring the fact that rotation data says this should be at top right or bottom left.

You are probably in a situation where all the other software you are using reads the orientation data and acts on it. And you're taking the pictures with a smartphone or an up to date camera that has the means to detect and report its orientation in the image meta data. (My own situation is that I use a camera that has no orientation sensor, so all images are presented in the default landscape orientation. I use Gimp or Irfanview to manually rotate them. When I do this, I invariably get a prompt to save the changed picture, so that the image is saved in the proper orientation.)

Please tell us where the image comes from, and what software you're using. You need a proper photo editor that actually rotates the image data and doesn't just fiddle with the rotation information.

I recall traveling abroad with a colleague who didn't know what time was. His smartphone might or might not have automatically changed to the local timezone, but it seemed he had no way to tell if it had done so.

Automation is fine if you know it has acted and you know what it has done. Like my colleague, you have tools that act autonomously without telling you what they have done.

Let me rephrase... Tbird always inserts this particular image rotated from portrait to landscape.

Quote: "Thunderbird has not rotated your pictures. It falls to act on embedded data included with some images that tells the displaying program how to rotate the image. It just shows the image with the pixel (0,0) at the top left, ignoring the fact that rotation data says this should be at top right or bottom left". In other words, Tbird HAS rotated the picture, in that it is ignoring the orientation data accompanying the image. This would be a failure in Tbird.

So you're telling me that in order to get Tbird to display images correctly, I have to download/install an image editing program, take a properly oriented image, rotate this image (from it's properly displayed portrait orientation) to landscape orientation (hopefully correctly guessing which way to rotate it) and insert it in Tbird to see if it inserts correctly? And if it still doesn't, download/install another editing program and do it all again, until Tbird finally sees something it likes and displays the image correctly? Am I understanding this correctly?

Quote: "...all the other software you are using reads the orientation data and acts on it..." But Tbird doesn't. Again, this is a problem with Tbird. If it's failing to act on instructions as to how to display the image correctly, then it is indeed rotating the image (or flipping it, or inverting it, or whatever). It's taking an image that is properly in portrait orientation, and is inserting it in some arbitrary manner, ignoring positioning instruction data. If everything that displays the image does so correctly, but Tbird does not, then Tbird has a problem, and needs to be patched/fixed.

I did indeed take the picture with a smartphone. I bluetoothed it over to my pc, and checked the image in Windows photo viewer. It displayed correctly. I inserted said image into Tbird, where it did not display correctly. Then I opened the original image in MSPaint, where again it displayed correctly, rotated it 90 degrees opposite to the way Tbird was displaying it (thinking that this might "cancel out" the undesired rotation), and "save file as" with a new name, then inserted that altered image into Tbird... where once again it was not displayed properly, rotating it to the opposite direction (still landscape, bit rotated 180 to the original insertion). So obviously Tbird is indeed reading some sort of orientational information, is it not?

I'm really not trying to be difficult or snarky here... I'm just trying to gain an accurate understanding of exactly what you're saying is going on. It still all sounds like a problem with Tbird to me, one that requires additional (and what should be un-necessary) steps to correct. I do know how to do this, but what if I were some little old grandma trying to send a Christmas pic to her grandkids? Is she going to know how to go about all this?

Again, I apologize if I'm coming across as an argumentative jerk... this is not deliberate or intentional.

Pictures are stored with pixel (0,0) at top left. If they have accompanying data that tells the viewing program to rotate it to some other orientation, and that viewing program honours such requests, then the image will be rotated at the point of being displayed to the appropriate orientation. The image itself as stored is not altered; it is simply painted to the canvas according to the rotation data.

Thunderbird is an email client, not a graphics program, and its design predates the use of smartphones with orientation detectors. It doesn't know or care about the orientation data embedded into images taken with such devices, and so it simply shows the image with pixel (0,0) at top left. Personally I am happy that it doesn't tamper with images.

You need to rotate that image yourself, rewriting it so that the visual top left is at pixel (0,0). That means using a graphic program to rewrite the image in the appropriate orientation.

I doubt that there is any graphics software, outside of a few special cases such as, maybe, face recognition, that is capable of "looking" at a picture and working out which way is up. This can be done if the camera reports the orientation at the time of taking the picture, and the display software knows what to with with the information stored in the exif metadata. For better or for worse, Thunderbird does not process exif metadata.

You need to understand whether the software you use to rotate the picture is actually remapping the pixels, or just fiddling with the rotation flag.

Try creating an image in Paint. Just a rectangle will do, so long as it has an obvious form factor that says which way up it is. If you create a tall narrow rectangle (portrait) image, Thunderbird will respect that and display it tall and narrow, thereby demonstrating that Thunderbird does NOT rotate images.

Attached is a screen shot of such a picture being shown in a received message in Thunderbird.

I know which way up my camera was when I took a picture, and I use appropriate software to turn an image round (and crop, or adjust colours etc etc) if necessary. I don't expect my email client, nor anyone else's software to do this automatically. I put the image the right way up myself, so I know it will unconditionally appear the right way up (as defined by me) to anyone who views it.

If you try taking pictures of the floor or ceiling your phone's orientation detector can become confused. I'm tired of watching videos that appear sideways because all the "smart" kit has taken these choices away from the user. If you care about your picture and want them to appear correctly, take control and fix the orientation yourself. Thunderbird is not the only software that won't auto-rotate images.

I believe there is or was an add-on that could rotate images in Thunderbird. I don't know if it worked on outgoing messages, or just on incoming messages. Either way, I'd want the image to be inherently and intrinsically the right way up, rather than hoping that everybody else's software will know what to do with it.

The Auto Resize Image add-on has an option to read (and presumably act upon) EXIF rotation data in images. So that is probably the "fix" you are seeking.

https://addons.mozilla.org/en-GB/thunderbird/addon/auto-resize-image/

Using it here has resulted in portrait mode images, taken with an Android smartphone, being delivered in portrait orientation. I don't know yet if it has simply rotated at point of display, or actually rewritten the images. It leaves me uneasy that some correspondents would still get incorrectly oriented images .

Thanks, Zenos, both for the education AND the add-on tip. It worked perfectly (at least this time... as you say, it may not always work that way.)

Very much appreciated. Guess I'll have to look into Gimp or Irfanview. Thought Gimp was a Linux program? No problem anyway... just set my pc up as a dual-boot Windows 10 / Deepin Linux system, so I can go either way.

Thanks again!!

Gimp is available on several platforms, but yes, is essentially a gnu program.

Irfanview works pretty well under Wine. ;-)