The problem with this idea is that most images are technically already compressed. GIF, JPEG, and PNG have, by design, built-in compression. If you try to ZIP one of these files, for instance, you will get very little compression... less than 5%. Other ways to compress images involve resizing, cropping, reducing colors, increasing compression (as in JPEG), etc... The problem is, the method will be less or more appropriate, depending on the image and its purpose. If I am sending an image and need it unchanged, I don't want some automated system changing it in the background.

If the changes take place in the foreground, then you are basically proposing adding minor image manipulation functionality into an email client. By combining every tool that you may ever want to use together into a single tool, you'd ultimately end up with an entire operating system with a bunch of tools to choose from... say, from a "start" menu. ;)

This is not something that could (or should) take place on the receiving end... because the receiving end can't be sure of the intention of the sender... and shouldn't be automatic on the sender's end, because the end result might be a bunch of headaches where images were changed in the background when you didn't want them to, and you have no idea until the receiver complains about a grainy image.

Also, the mailbox limit is usually on the receiving end. So, unless the mail client will be self-aware of the limits of the receiver's inbox, it can't easily make a determination as to whether or not this should take place.

Another heads up... if a 3 megabyte file is attached to an email, the resulting email is likely to become 5 megabytes. This is because attachments are encoded in such a way that they take up more space. This is needed due to the limited character-set that emails allow as they traverse the Internet.

Anyway, nice idea... but I'm afraid, in my humble opinion, that there just isn't a feasible way to tackle this particular problem... at least not through "compression".

not a good thing its useless

cool.