Images inbedded in email have wrong orientation

Usually you do NOT want Mail (or any other
email client) modifying the files that you
are sending.

Inline graphics seem like an obvious exception to
this -- typically, you would want their orientation
to be right side up for the viewer's convenience.

Actually, it depends on the context. If I were submitting the photograph to be processed by someone for publication, for example, I definitely would not want some program modifying the image for me.

I expect my mail program to send the attachment exactly like my original file. If it changes stuff behind my back, then it can lead to problems like the recipient seeing something different than me because our files our now different.

Actually, it depends on the context.

Of course. I would prefer that Mail give me complete control of such things, but I could accept the action of my inserting a graphic in between other elements of a message is a reasonable indicator that the intended context is inline viewing, & thus that automatically orienting a suitably tagged image file is a "feature, not a bug" of the app, particularly if a preference setting allowed it to be turned on or off as a global option.

Better still, I would like the option to rotate any displayed image for sending as a contextual popup option, plus "badges" (viewable only locally) to indicate such things as rotation has been applied, exif orientation info is available, etc. I would like to see this extended to other options useful for inline images, such as cropping or down-sampling, which would also change the file itself, but only the sent item, not the original.

Basically, anything that you should be able to do with Preview & "save as," you should be able to do inside the body of the message ... if you want to. The idea is to cut down the number of steps involved with as little clutter & as much transparency as is consistent with not doing anything behind the user's back.

Toward this end, I would very much like Mail to make the raw source of both new & draft messages available for viewing before sending them. Annoyingly, this is not currently possible, so the only way to be sure of what you are sending is to send it.