即使我正确设置了 postfix 和 dovecot，我的收件箱仍然无法使用。它本来可以正常工作，但突然就无法使用了。我的日志中出现了这个信息，这是什么？指定的用户不存在，并且重复使用了不同的用户名。
Apr 02 12:43:11 auth: Debug: client passdb out: FAIL 11 [email protected]
Apr 02 12:43:09 auth: Debug: auth([email protected],194.169.175.10): Auth request finished
Apr 02 12:43:09 auth: Debug: sql([email protected],194.169.175.10): Finished passdb lookup
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: Finished: user_unknown
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): Finished passdb lookup
Apr 02 12:43:09 auth-worker(31679): Info: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): unknown user
Apr 02 12:43:09 auth-worker(31679): Debug: mysql(localhost): Finished query 'SELECT username AS user,password FROM mailbox WHERE username = '[email protected]' AND active='1'' in 0 msec
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): query: SELECT username AS user,password FROM mailbox WHERE username = '[email protected]' AND active='1'
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: sql([email protected],194.169.175.10 ): Performing passdb lookup
Apr 02 12:43:09 auth-worker(31679): Debug: conn unix:auth-worker (pid=24864,uid=128): auth-worker<46>: Handling PASSV request
Apr 02 12:43:09 auth: Debug: sql([email protected],194.169.175.10): Performing passdb lookup
Apr 02 12:43:09 auth: Debug: client in: CONT 11 MXEydzNlNHI= (previous base64 data may contain sensitive data)
Apr 02 12:43:03 auth: Debug: client passdb out: CONT 11 UGFzc3dvcmQ6
Apr 02 12:43:03 auth: Debug: client in: CONT 11 bWlkZ2V0QHdlYmxhbmQuZnVu (previous base64 data may contain sensitive data)