As suggested earlier, I deleted all .imap directories and the log sync errors stopped - for a while. They have now returned. It seems to happen for every mailbox that gets accessed. Dovecot version 2.1.1 with pidgeonhole 3.0.0 on Mandriva Linux. Could this interfere with sieve filters? Several users have filters but none of them seem to do anything. Mar 7 09:25:51 server dovecot: imap(john): Error: Log synchronization error at seq=2,offset=38708 for /home/john/Mail/INBOX/.imap/Weather Summaries/dovecot.index: Extension header update points outside header size Mar 7 09:25:51 server dovecot: imap(john): Error: Log synchronization error at seq=2,offset=41576 for /home/john/Mail/INBOX/.imap/Zerna/dovecot.index: Extension header update points outside header size Cheers and thanks, Stephen -- ============================================================================Stephen Davies Consulting P/L Voice: 08-8177 1595 Adelaide, South Australia. Fax : 08-8177 0133 Records & Collections Management. Mobile:040 304 0583