I was going to test 1.1.16 so as to see how it handles global ACLs (in the hope to have a possible comparison with 1.2.0's odd behavior), when I encountered the problem described hereafter. Note that just disabling ACLs is sufficient to get back a fully functional imap binary. So, should there be some plans for a 1.1.17 version, perhaps could the info provided here prove somewhat useful. Folowing telnet session: # telnet 127.0.0.1 imap Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. * OK Dovecot ready. a1 login testuser ****** a1 OK Logged in. Connection closed by foreign host. yields this in mail.log: dovecot[18129]: imap-login: Login: user=<testuser>, method=PLAIN, rip=127.0.0.1, lip=127.0.0.1, secured dovecot[18129]: IMAP(testuser): Loading modules from directory: /usr/ local/dovecot-1.1.16/lib/dovecot/imap dovecot[18129]: IMAP(testuser): Module loaded: /usr/local/ dovecot-1.1.16/lib/dovecot/imap/lib01_acl_plugin.so dovecot[18129]: IMAP(testuser): Effective uid=2001, gid=2001, home=/ Volumes/ALMbpSpare/People/a/testuser dovecot[18129]: IMAP(testuser): mbox: data=~/_mailboxes:INBOX=~/ _mailboxes/inbox:CONTROL=~/_mboxesctrl dovecot[18129]: IMAP(testuser): fs: root=/Volumes/ALMbpSpare/People/a/ testuser/_mailboxes, index=, control=/Volumes/ALMbpSpare/People/a/ testuser/_mboxesctrl, inbox=/Volumes/ALMbpSpare/People/a/testuser/ _mailboxes/inbox dovecot[18129]: IMAP(testuser): acl: initializing backend with data: vfile:/usr/local/etc/dovecot-acls dovecot[18129]: IMAP(testuser): acl: acl username = testuser dovecot[18129]: IMAP(testuser): acl: owner = 1 dovecot[18129]: IMAP(testuser): acl vfile: Global ACL directory: /usr/ local/etc/dovecot-acls dovecot[18129]: child 18272 (imap) killed with signal 11 (core dumps disabled) and this crash log: Process: imap [18272] Path: /usr/local/dovecot-1.1.16/libexec/dovecot/imap Identifier: imap Version: ??? (???) Code Type: X86 (Native) Parent Process: dovecot [18129] Date/Time: 2009-07-04 18:55:46.552 +0200 OS Version: Mac OS X 10.5.7 (9J61) Report Version: 6 Anonymous UUID: EE838D90-3F91-46F8-9CDA-3611674B371F Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: KERN_INVALID_ADDRESS at 0x00000000d0201332 Crashed Thread: 0 Thread 0 Crashed: 0 ??? 0x000b87bf static_system_pool + 27 1 lib01_acl_plugin.so 0x0011b871 acl_cache_right_lookup + 33 (acl-cache.c:146) 2 lib01_acl_plugin.so 0x0011b9a6 acl_cache_mask_init + 182 (acl-cache.c:105) 3 lib01_acl_plugin.so 0x00118cf8 acl_backend_init + 376 (acl-backend.c:76) 4 lib01_acl_plugin.so 0x0011d269 acl_mailbox_list_created + 217 (acl-mailbox-list.c:429) 5 imap 0x00053a0a mailbox_list_init + 410 (mailbox-list.c:220) 6 imap 0x000344c5 mbox_create + 645 (mbox- storage.c:471) 7 imap 0x00052f40 mail_storage_create + 272 (mail-storage.c:224) 8 imap 0x00050978 mail_namespaces_init + 1096 (mail-namespace.c:230) 9 imap 0x00011ab9 main + 1065 (main.c:238) 10 imap 0x00001646 start + 54 Thread 0 crashed with X86 Thread State (32-bit): eax: 0x00200a00 ebx: 0x00118b8b ecx: 0x002009d0 edx: 0x002009d0 edi: 0x00200a00 esi: 0x0011da28 ebp: 0xbffff158 esp: 0xbffff13c ss: 0x0000001f efl: 0x00010282 eip: 0x000b87bf cs: 0x00000017 ds: 0x0000001f es: 0x0000001f fs: 0x00000000 gs: 0x00000037 cr2: 0xd0201332 Binary Images: 0x1000 - 0xb6fe0 +imap ??? (???) <e5ae287e992319a2faf58982a15102be> /usr/local/dovecot-1.1.16/libexec/ dovecot/imap 0x118000 - 0x11dff7 +lib01_acl_plugin.so ??? (???) <24284783dc3113906f90a37bdd1fce02> /usr/local/dovecot-1.1.16/lib/ dovecot/imap/lib01_acl_plugin.so 0x8fe00000 - 0x8fe2db43 dyld 97.1 (???) <100d362e03410f181a34e04e94189ae5> /usr/lib/dyld 0x9013c000 - 0x90143fe9 libgcc_s.1.dylib ??? (???) <f53c808e87d1184c0f9df63aef53ce0b> /usr/lib/libgcc_s.1.dylib 0x913ba000 - 0x91521ff3 libSystem.B.dylib ??? (???) <b47c8e6e45aef620730710a732bf1930> /usr/lib/libSystem.B.dylib 0x92f5f000 - 0x92f63fff libmathCommon.A.dylib ??? (???) /usr/lib/ system/libmathCommon.A.dylib 0x97038000 - 0x9712cff4 libiconv.2.dylib ??? (???) <c508c60fafca17824c0017b2e4369802> /usr/lib/libiconv.2.dylib 0xffff0000 - 0xffff1780 libSystem.B.dylib ??? (???) /usr/lib/ libSystem.B.dylib This is the output of dovecot -n: # 1.1.16: /usr/local/etc/dovecot.conf # OS: Darwin 9.7.0 i386 protocols: pop3 imap ssl_disable: yes disable_plaintext_auth: no login_dir: /usr/local/var/run/dovecot/login login_executable(default): /usr/local/dovecot-1.1.16/libexec/dovecot/ imap-login login_executable(imap): /usr/local/dovecot-1.1.16/libexec/dovecot/imap- login login_executable(pop3): /usr/local/dovecot-1.1.16/libexec/dovecot/pop3- login first_valid_uid: 2001 mail_location: mbox:~/_mailboxes:INBOX=~/_mailboxes/inbox:CONTROL=~/ _mboxesctrl mail_debug: yes mbox_read_locks: flock mbox_write_locks: flock dotlock mail_executable(default): /usr/local/dovecot-1.1.16/libexec/dovecot/imap mail_executable(imap): /usr/local/dovecot-1.1.16/libexec/dovecot/imap mail_executable(pop3): /usr/local/dovecot-1.1.16/libexec/dovecot/pop3 mail_plugins(default): acl mail_plugins(imap): acl mail_plugins(pop3): mail_plugin_dir(default): /usr/local/dovecot-1.1.16/lib/dovecot/imap mail_plugin_dir(imap): /usr/local/dovecot-1.1.16/lib/dovecot/imap mail_plugin_dir(pop3): /usr/local/dovecot-1.1.16/lib/dovecot/pop3 pop3_lock_session(default): no pop3_lock_session(imap): no pop3_lock_session(pop3): yes pop3_uidl_format(default): %08Xu%08Xv pop3_uidl_format(imap): %08Xu%08Xv pop3_uidl_format(pop3): %08Xv%08Xu auth default: debug: yes passdb: driver: pam args: * userdb: driver: passwd plugin: acl: vfile:/usr/local/etc/dovecot-acls