問題解決

1. INBOX 檔案太大，無法寫入。

   [root@mail ~]# grep -m1 'failed to store' /var/log/maillog
   Apr 22 04:10:12 localhost dovecot: lda(dywang): Error: sieve: msgid=...:
    failed to store into mailbox 'INBOX': Internal error occurred.
    Refer to server log for more information.
   

2. 解決：檢查 main.cf 設定，不足的話加大後重啟 postfix。

   [root@mail ~]# vim /etc/postfix/main.cf
   [root@mail ~]# grep mailbox_size_limit /etc/postfix/main.cf
   mailbox_size_limit=512000000
   [root@mail ~]# /etc/init.d/postfix restart
   Shutting down postfix:                                     [  OK  ]
   Starting postfix:                                          [  OK  ]