Heimo Claasen <[EMAIL PROTECTED]> wrote on Sun, 26 Nov 2000:
>The quite practical - and as "safe" considered - functionality with
>Nettamer (and I think, of other mailer clients too, with DOS and other
>OSs) to "delete old" mails with a next connection to the mailserver
>has become problematic: ...
> ...
>This worked quite fine, as a safety net and for cases of problematic
>download conditions.
> ...
>I think this is a very bad development. And a case for revision of the
>POP3 RFCs.
The working of the Internet depends on sticking to standards
(RFCs) and not on relying on implementation details of specific
programs (which may change at any time). So, let us look at how
the IETF (Internet Engineering Task Force) would judge the
reported situation:
1. The POP3 protocol (RFC 1939) never guaranteed anything about
the sequence of mails in a POP3 account between 2 succeeding
connections to the POP3 host.
If an e-mail client depends on the behaviour of some POP3
implementations which do keep this sequence stable over
different connections, then this e-mail client is simply
faulty - it relies on implemention details, not on RFCs.
The only correct way of referring to the same e-mail message
on the POP3 server across different logins, is the UIDL
(unique id listing) command. This command is, however, an
optional feature that is not guaranteed to be available on
every POP3 hosts.
2. A POP3 download via the command "RETR(ieve) <nbr>" does _not_
delete the downloaded mail from the POP3 server. So there is
really no reason to use the sequence of mails as "a safety net
for problematic download conditions". The mail (whether
downloaded or not) is deleted only when the POP3 client (i.e.
_your_ software, not the provider's) explicitely issues a
"DELE(te) <nbr>" command to the POP3 server.
3. The POP3 protocol was never intended for managing e-mails on
the server. The proper protocol for server based e-mail
management is IMAP4 (RFC 2060).
So, in summary:
(a) If Nettamer really does what you reported, this is not a
feature, but a faulty behaviour, and the program (not the
POP3 standard) should get fixed.
(b) Even with a very bad connection, a POP3 download can never
lose e-mails as long as the client program works correctly
per the RFCs.
(c) If you wish your e-mails to stay on the server (e.g. because
you often switch computers and want to keep your mail folders
on the server instead of on your hard disk), then you should
look for a provider (and client program) which supports the
IMAP4 protocol.
- Wolfgang Redtenbacher
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