邮件已送达，但 courier-imap 拒绝连接

Question

我的邮件服务器以 Maildir 格式成功发送邮件。但我无法通过 IMAP 连接到快递。它拒绝连接。防火墙143端口已打开。服务器运行的是 openSUSE 13.2。这是我的配置文件/etc/courier/imapd（删除了注释以便更好地查看）：

ADDRESS=***
PORT=143
MAXDAEMONS=40                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              
MAXPERIP=20                                                                                                                                                                                                                                                                    
PIDFILE=/run/imapd.pid
TCPDOPTS="-nodnslookup -noidentlookup"
LOGGEROPTS="-name=imapd"
IMAP_CAPABILITY="IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE"
IMAP_KEYWORDS=1
IMAP_ACL=1
IMAP_CAPABILITY_ORIG="IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA AUTH=CRAM-MD5 AUTH=CRAM-SHA1 AUTH=CRAM-SHA256 IDLE"
IMAP_PROXY=0
IMAP_PROXY_FOREIGN=0
IMAP_IDLE_TIMEOUT=60
IMAP_MAILBOX_SANITY_CHECK=1
IMAP_CAPABILITY_TLS="$IMAP_CAPABILITY AUTH=PLAIN"
IMAP_CAPABILITY_TLS_ORIG="$IMAP_CAPABILITY_ORIG AUTH=PLAIN"
IMAP_DISABLETHREADSORT=0
IMAP_CHECK_ALL_FOLDERS=0
IMAP_OBSOLETE_CLIENT=0
IMAP_UMASK=022
IMAP_ULIMITD=65536
IMAP_USELOCKS=1
IMAP_SHAREDINDEXFILE=/etc/courier/shared/index
IMAP_ENHANCEDIDLE=0
IMAP_TRASHFOLDERNAME=Trash
IMAP_EMPTYTRASH=Trash:7
IMAP_MOVE_EXPUNGE_TO_TRASH=0
SENDMAIL=/usr/sbin/sendmail
HEADERFROM=X-IMAP-Sender
IMAPDSTART=YES
MAILDIRPATH=Maildir

如果您需要任何其他文件来解决问题，请告诉我。