[Dovecot] Question about pop3_reuse_xuidl

Hi,

we are in migration progress from Communigate Pro 5.0.x to Dovecot 2.0.15 with mdbox. We still migrated about 25.000 IMAP accounts from CGP to Dovecot.

Also there were still added about 2000 new POP3 Accounts on Dovecot.

Now we must migrate about 10.000 POP3 accounts from CGP to Dovecot.

At the beginning of our migration we didn't set the "pop3_reuse_xuidl" configuration option to yes. Do you know what happens when we activate the "pop3_reuse_xuidl" option on our running dovecot?

Will Dovecot change the uidl value for all existing mails which have set "X-UIDL" in its mailheader, or does Dovecot only change the uidl value for new received and still not downloaded mails?

Many thanks and regards Urban Loesch