Scenario: Using Dovecot 0.99.10.9 as pop3 server. With delete on retrival off.

clients: outlook*

Problem: Everytihng work perfectly, except that outlooks keeps re-downloading SOME mail over and over. Though it already got them. No obvious pattern which, but only a small percentage.

First of I looked at dovecots UIDLs. Initialy I thought it's broken (see my previous thread) Sorry for even thinking that, it's ok, my bad :) Rather, outlooks UIDL handling seems to be very broken :(

But I think I found an easy workaround.

Dovecots UIDLS seem to be

timestamp.message#

eg.

1 1093990148.1 2 1093990148.2 3 1093990148.3 4 1093990148.4 5 1093990148.5 6 1093990148.6 7 1093990148.7 8 1093990148.8 9 1093990148.9 10 1093990148.10 11 1093990148.11 12 1093990148.12

The problems started with #10

-> Asumption: outlook falsy only takes a fixed numbers of chars to hold the UIDL, the rest ist ignored. Perhaps only the first 13 or so.

What I did is reversing the order in UIDL generation. Instead of

timestamp.message# -> message#.timestamp.

Seems to work perfectly.

Well, a bit too early too tell if it really works. Need to wait a couple of days and see if the problem re-appears or not.

The only thing I'm 100% sure is that outlooks UIDL handling is broken.

BTW: very nice source code. Very easy to follow, took me 5 minutes to find the correct .c and routine.

In /pop3/command.c, list_uids() all I changed is

... mail->seq, client->uidvality, mail->uid to mail->seq, mail->uid, client->uidvality. (2 times)

If anyone is interested, I'll keep you informed if the problem is really gone with this mini-patch.