File sizes
If I do some bitmap editing using Corel and want to send the image as an email attachment, I save (export actually) the file as a JPEG to "My Documents" or whatever. Then, I open my email programme, write the text, attach the file and send. Some of the attachments turn out to be really large though and take my old steam-driven computer ages to actually send.
What is a good way of reducing the size of the attachment? Save it as a JPEG, GIF, TIF ... is there any difference between these? Does physically reducing the size of the image (scaling) make any difference to the resulting file size?