Various option
Fisrtly you cannot really reduce an image's file size without degrading it. However you can rduce the file size and still have an image that looks good on screen. Ifranview or GIMP will do that for you for free.
Photobucket or Flickr etc. woudl let you upload and share the images with either people you choose or the world at large.
If you want to send large images and get webspace with your email account you could ftp (FTP = file transfer protocol) them to your web space / ftp server space for whoever needs them to download. FileZilla if a good free ftp package.
Best regards
Memetic.