测试连接

测试SMTP协议

telnet mail.52progress.com 18025

测试POP3协议

telnet mail.52progress.com 110

偶遇

1. 503 5.5.1 Error: authentication not enabled 修改/etc/postfix/main.cf，把smtpd_tls_auth_only置为no即可

smtpd_tls_auth_only = no

2. 测试Dovecot的pop3协议时，报错 -ERR [AUTH] Authentication failed -ERR [SYS/TEMP] Internal error occurred. Refer to server log for more information