Image Crunching & Resizing

Hi
So if I have an image upload field…
Is there a simple way to optimize (Compress & Resize) those uploaded images on the fly, so that the crunched version I receive as an email attachment is a reasonable size?
I realise that this optimisation may put some load on the server (maybe there is a way to manage/limit this load?), but I also want to avoid large files being slow to upload and taking up too much space on the server, even if it’s only temporary..
And I certainly dont want my email clogged up with massive images either.
Thanks so much for your help, your wisdom is very much appreciated.
(I think contact form 7 rocks by the way)