there is also the newer g-mail, as opposed to e-mail. a lot of e-mail servers limit you to 10 megabytes in file size, and that's total space. g-mail limits you to 1 gigabyte. this was something piloted by google and for a while it was somewhat difficult to get a g-mail account. you had to have someone refer you before you could get such an account, as it was in beta. i'm not quite sure what the status is of g-mail currently, if you need a referral still or if it's out of beta, but it shld be fairly easy to get an account now. i'm also not sure how someone without a g-mail account could send you a very large file if they didnt also have g-mail, so you might want to check all these unknowns out.
if you're going to send anything electronically, file size is important, and therefore the resolution of the scan is important. the higher the resolution of the scan, the bigger the file size is going to be. thus, if you scan a 4 x 6 print in at 600 dpi (dots per inch), the file size may be too large for normal e-mail. but in doing restorations and so on you want as much detail as possible, so it's a bit of a conundrum at times to get a smaller file size for sending and a larger file size for detail.
and that brings us to zip and rar. .zip is a file extension used by winzip. winzip is a packing and compression program. it will take any electronic file on your computer and essentially compress it down in size, often by quite a bit. you can also add other files to a .zip file and send them all at once. the person on the other end simply unpacks and uncompresses the file back into the original state by using the same or similar program. thus, you might send a file that was originally 40 megs as 25 megs. compression rates will differ depending on the original file. rar is simply another type of this program using a different extension. rar is often used in europe where zip is often used in the states. it's good to have both programs, however.
packing and compression programs like winzip and winrar are different from .jpeg compression. converting a file to .jpeg/jpg actually causes some data to be lost (unless you use a 1 to 1 ratio when converting to .jpg. using a zip program loses nothing. zip programs use a routine that removes file data in a specific manner such that when restoring it it simply replaces that removed data, so nothing is lost.
thus, you might be able to get the client to scan, zip and send a file by regular email... maybe
K.