Hi !
POP3-RFC (1939) speaks about UIDL command: The unique-id of a message is an arbitrary server-determined string, consisting of one to 70 characters in the range 0x21 to 0x7E, which uniquely identifies a message within a maildrop and which persists across sessions.
When I issue an UIDL command (dovecot 0.99.10.9) I get replies like
1 1093990148.1 2 1093990148.2 3 1093990148.3 ... .
You see the problem ? '0'-'9' and '.' are not in range 0x21-0x7E !
Currently I'm tracking down a nasty problem with Outlook 2003 together with dovecot acting as pop3 server. Multile pop3 accounts, with 'leave mail on server' on. (cant turn it off) for no apparent reason, a couple of mails (just a few out of thousands/hundrets) get re-downloaded again, and again, and again ... as if client had not seen it before. Might be a client problem ... while trying to find out the reason for this behaviour if found this UIDL thing.
I fear it might not be the true reason/problem for my problems with outlook redownloading certian mails forevr, but I thought it doesnt hurt to report it ;)