利用 perdition 代理 imap
背景
最近公司需要将 263 企业邮箱迁移到 office365 上，需要将以前的旧邮件迁移到新邮箱中，方便查看历史记录。但是，迁移的速度非常之慢，经常有迁移失败的。错误如下：
错误: TooManyTransientFailureRetriesPermanentException/RemoteNetworkErrorTransientException/IOException/SocketException: Error: The job encountered too many transient failures (310) and is quitting. The most common failure is RemoteNetworkErrorTransientException/IOException/SocketException with the hit count 60. --> We were unable to reach your email provider. Please check your server settings, or try again later. --> Unable to read data from the transport connection: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond. --> A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
看不出来到底是 263 的问题还是 office365 的问题，中间加个代理就方便观察、测试到底哪边的问题了。
关于 imap 的代理，网上实在是太少。踩了几个坑，在此记录下。
测试了以下几个程序：
- Nginx，网上文章都说可以代理，但需要单独的用户认证，怎么将用户认证重定向到 263 的用户认证，这个没法搞定。[1][2]
- IMAP-Proxy，只有 Python 代码，没有程序。跑了代码有错，没法用。
- SquirrelMail imap proxy，这个没找到教程，根本不知道怎么配置。看配置文件中的哪些配置项，尝试配了一些，没法启动成功。
- Perdition，这个成功了。
安装
CentOS 7
yum install perdition
Ubuntu
apt install perdition
配置
新建文件 /etc/perdition/perdition.imap4.conf
outgoing_server imap.263.net log_facility local5 no_lookup timeout 40 imap_capability "IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA ACL ACL2=UNION STARTTLS" ssl_mode tls_listen ssl_cert_file /ca/test.pem ssl_key_file /ca/test.key
新建文件 /etc/perdition/perdition.imap4s.conf
outgoing_server imap.263.net log_facility local5 no_lookup timeout 40 imap_capability "IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA ACL ACL2=UNION STARTTLS" outgoing_port 143 ssl_mode ssl_listen ssl_cert_file /ca/test.pem ssl_key_file /ca/test.key
Ubuntu 需要修改 /etc/default/perdition，将里面的 POP3 和 POP3S 设置成 no。
启动服务
CentOS 7
systemctl restart perdition-imap4 systemctl restart perdition-imap4s
Ubuntu
service perdition restart
