POP3 "resume download" extension

I've had some thoughts about an extension to POP3 that will let you
resume a download of an interrupted transfer. These days people tend to
send each other messages with large attachment, 2-3Mb is not that
uncommon. Many clients connecting to their ISP, or even the ISP itself,
have their modems improperly setup which causes a flaky phoneline,
resulting in a premature disconnect.

At present, these messages will have to be re-downloaded from scratch
taking a lot of unnecessary bandwidth from the ISP, not to mention
resources within the system itself. Since a majority of the ISPs today
are still using POP3, as opposed to IMAP (mostly due to the reduced
diskspace required when serving a huge numbers of users), I think this
might be a good idea.

I've spent the last week discussing and developing the idea with a few
people, and they are all backing up the idea. I now felt it was time to
take it to this group in order to get a response from a larger group.

We all came to the conslusion that by giving the RETR command a second
argument specifying the offset of where to start downloading would
probably be the best idea. Also, there was a discussion on wheather an
octet range, (a third argument, specifying where the end of the download
should take place) would be appropriate now that we see a lot more
portable internet devices where bandwidth is scarce.

A breakdown on savings:

1) Less consumption of bandwidth
2) Less resources used on the servers
3) ISPs wishing to have this feature will not be forced to deploy an
IMAP server

Not to mention happier users getting their files faster and cheaper (in
Sweden, and most other countries in Europe, flatrates are just a mere
dream).

// Anders Rundegren