[POP before SMTP]
> But in practice the user is more likely to connect roughly simultaneously;
> obviously if they're using unix you can ask just ask them to make sure they
> run fetchmail (or whatever) before doing a queue run, but I'm not sure what
> all the PC email packages do, if any of them do it in the wrong order then
> they won't be able to use your service.
I believe that many PC email packages automatically make a POP connection
before every SMTP connection, as a weak form of security even if the user
did not ask to fetch incoming mail. It's also easy to set up a web page
for users to authenticate themselves (via username and password) and
request that their IP address gets added to the "OK" list for a while.
> That may or may not be a problem: if it's for a company system you can
> presumably just tell them to use the right software, which obviously
> wouldn't be acceptable for an ISP.
The issue is not what software they use, but what protocols thay speak,
and in what order. It would be quite acceptable for an ISP to require POP
before SMTP, and I know several ISPs that do so. Remember that POP before
SMTP would be required only for roaming users (who are temporarily using
another ISP's dialup service, but want to use their home ISP's SMTP
server).
--apb (Alan Barrett)
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