Re: [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

[Dovecot] UIDL and IMAP

[Kenneth Porter]

I finally got my aging FC2 box retired and moved all email to my new CentOS 
5 box. My site is all-IMAP, no POP3.


I have one user who downloads all email to Thunderbird on his laptop so 
that he can work offline while away from a network connection (eg. on an 
airplane). I forgot to change the pop3_uidl_format setting as described 
here:


http://wiki.dovecot.org/Upgrading/1.0

So he was seeing repeated downloads of all his mail (about 300 MBytes) 
every time he connected. (I'm not sure why it didn't happen only the first 
time.) I changed the setting and haven't heard back whether if fixed things 
for him.


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.


CentOS 5 is currently shipping with:

dovecot-1.0-1.2.rc15.el5

I may look for a newer release. CentOS, based on RHEL, is intended to be a 
conservative distro, so I'll probably need to look at RPMForge (an addon 
repository of more exotic and bleeding edge software) to see if it offers a 
newer release.