Every now and then, I have the situation to send one or more large image files via E-Mail. The images should be reduced in size first, so my immediate impulse is the wish to have an item for this purpose in the image file's context/Actions menu. I am not sure how many people would have a similar use case. At least, there are some articles in the web like this [1]. It would be nice to have a simple tool integrated by default in the context menu to reduce the image size to predefined value. See also [2]. [1] https://www.howtogeek.com/109369/how-to-quickly-resize-convert-modify-images-from-the-linux-terminal/, 2015 [2] http://www.ubuntubuzz.com/2015/10/how-to-add-right-click-convert-and-resize-images-nautilus.html
This should be done by the email client. In Apple land, macOS Mail has this feature. Can you file a new bug requesting this for KMail? Here's the ticket tracking the feature for Thunderbird: https://bugzilla.mozilla.org/show_bug.cgi?id=401991 (and an add-on accomplishes it, too: https://addons.mozilla.org/en-US/thunderbird/addon/auto-resize-image/)
I also think this should be handled by the email client. On the other hand, if we had this in the file manager, then one didn't have to wait for the favorite email client to implement this feature. The Mozilla Thunderbird bug is 10 years old. Thanks for the hint with the Thunderbird extension. Sadly, it doesn't work out of the box. There is a pretty sophisticated settings dialog. Maybe I missed something.