[Dovecot] UIDL and IMAP

[Benjamin R. Haskell]

[I didn't see a response to this on-list. Sorry if I'm repeating someone.]

On Mon, 1 Oct 2007, Kenneth Porter wrote:

> [...] I forgot to change the pop3_uidl_format setting [...]
> So he was seeing repeated downloads of all his mail (about 300 MBytes) every 
> time he connected. [...]
>
> Does this setting in fact get used by IMAP? It's in the POP3 section, so I'm 
> wondering if it takes effect when one is using IMAP from the client.


No, it doesn't. IMAP unique identifiers are always 32-bit 
(unsigned) integers, expressed in base 10. (64 bits when combined with the 
32-bit UIDVALIDITY)

cf. RFC 3501 - IMAP 4rev1
discussion: http://tools.ietf.org/html/rfc3501#section-2.3.1.1
syntax: uniqueid - http://tools.ietf.org/html/rfc3501#page-91

POP3 UID's have significantly more variation (hence the dovecot setting):

[ from RFC 1937 - POP 3 - http://tools.ietf.org/html/rfc1939#page-12 ]
“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.”

Best,
Ben