hi: I was using scientific linux 6 and had cache problem. I upgrade to scientific linux 7 but the problem is the same, so I try to find out why. dovecot version: 2.2.10. postfix + postfixadmin environment. use dovecot-lda to deliver local mail. if I enable cache with "auth_cache_size = 102400" and enable cram-md5 with "auth_mechanisms = plain login cram-md5". I have cache problem: if I change password at postfixadmin, I can not use the new password to login imap when old password is cached. dovecot log below: Jun 28 11:50:32 auth: Debug: client in: AUTH 6 CRAM-MD5 service=imap securedsession=xjn534sZ9gB/AAAB lip=127.0.0.1 rip=127.0.0.1 lport=143 rport=36342 Jun 28 11:50:32 auth: Debug: client passdb out: CONT 6 PDQzNTU5NTA4MTQxODg5NzUuMTQzNTQ2MzQzMkBtYWlsLmxoeS5jb20udHc+ Jun 28 11:50:32 auth: Debug: client in: CONT<hidden> Jun 28 11:50:32 auth: Debug: cache(test at test.example.com,127.0.0.1,<xjn534sZ9gB/AAAB>): hit: <hidden> user=test at test.example.com userdb_home=/share/postfix/domains/test.example.com/test/home userdb_mail=maildir:/share/postfix/domains/test.example.com/test userdb_uid=143 userdb_gid=143 Jun 28 11:50:32 auth: Info: cram-md5(test at test.example.com,127.0.0.1,<xjn534sZ9gB/AAAB>): password mismatch Jun 28 11:50:34 auth: Debug: client passdb out: FAIL 6 user=test at test.example.com Jun 28 11:50:34 imap-login: Debug: Ignoring unknown passdb extra field: Jun 28 11:50:34 imap-login: Info: Disconnected (auth failed, 1 attempts in 2 secs): user=<test at test.example.com>, method=CRAM-MD5, rip=127.0.0.1, lip=127.0.0.1, secured, session=<xjn534sZ9gB/AAAB> if I disable "cram-md5" with "auth_mechanisms = plain login". everything is fine. dovecot log below: Jun 28 11:32:24 auth: Debug: cache(test at test.example.com,127.0.0.1,<WNsin4sZ6gB/AAAB>): hit: <hidden> user=test at test.example.com userdb_home=/share/postfix/domains/test.example.com/test/home userdb_mail=maildir:/share/postfix/domains/test.example.com/test userdb_uid=143 userdb_gid=143 Jun 28 11:32:24 auth: Info: cache(test at test.example.com,127.0.0.1,<WNsin4sZ6gB/AAAB>): Password mismatch Jun 28 11:32:24 auth-worker(3711): Debug: sql(test at test.example.com,127.0.0.1): query: SELECT username as user, password, '/share/postfix/domains/test.example.com/test/home' as userdb_home, 'maildir:/share/postfix/domains/test.example.com/test' as userdb_mail, 143 as userdb_uid, 143 as userdb_gid FROM mailbox WHERE username = 'test at test.example.com' AND active = '1' Jun 28 11:32:24 auth: Debug: client passdb out: OK 15 user=test at test.example.com Jun 28 11:32:24 auth: Debug: master in: REQUEST 1951268865 3672 15 0b198494a7e732324f6d6c507b25c13e session_pid=3956 request_auth_token Jun 28 11:32:24 auth: Debug: prefetch(test at test.example.com,127.0.0.1,<WNsin4sZ6gB/AAAB>): success Regards, tbskyd