[Dovecot] Changing pop3_uidl_format

[Jeff Simmons]

I recently set up an OpenBSD - Dovecot mail server for a client. Naturally 
(according to Murphy's Law) they want to use Outlook 2003, pop3s, and leave 
messages on the server. And just as naturally, the UIDLs don't seem to be 
working, and when they download mail, they get EVERY email stored on the 
server, not just the new ones.

Other than switching them over to IMAP, I found the following in the Wiki 
documentation:

#POP3 UIDL format to use. You can use following variables:
  
  # %v - Mailbox UIDVALIDITY
  # %u - Mail UID
  # %m - MD5 sum of the mailbox headers in hex (mbox only)
  # %f - filename (maildir only)
  
  #If you want UIDL compatibility with other POP3 servers, use:
  # UW's ipop3d         : %08Xv%08Xu
  # Courier version 0   : %f
  # Courier version 1   : %u
  # Courier version 2   : %v-%u
  # Cyrus (<= 2.1.3)    : %u
  # Cyrus (>= 2.1.4)    : %v.%u
  
  #Note that Outlook 2003 seems to have problems with %v.%u format which is
  #Dovecot's default, so if you're building a new server it would be a good
  #idea to change this. %08Xu%08Xv should be pretty fail-safe.
  pop3_uidl_format = %v.%u

So my question is, what happens if I just change pop3_uidl_format to 
%08Xu%08Xv and restart the server? Will it just change things over to the way 
I want them, or will it blow up all the existing mail already being stored 
there?

Inquiring minds want to know. Thanks for any help you can provide.

-- 
Jeff Simmons                                   jsimmons at goblin.punk.net
     Simmons Consulting - Network Engineering, Administration, Security

                "It was on fire when I got here."