==== 必填信息。没有填写将不予回复 ====
- iRedMail 版本号：0.94
- 使用哪个数据库存储用户帐号（OpenLDAP，MySQL，PostgreSQL）：MySQL
- 使用的 Linux/BSD 发行版名称及版本号：Ubuntu14.04
- 与您的问题相关的日志信息：/var/log/mail.log
====
出现大量的日志  平均 2-3秒一条，最近几天出现
May 22 06:52:35 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:35 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:52:37 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:52:37 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:37 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:52:41 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:52:41 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:41 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:52:43 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:52:43 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:43 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:52:47 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:52:47 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:47 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:52:49 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:52:49 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:49 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:52:53 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:52:53 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:53 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:52:55 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:52:55 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:55 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:52:59 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:52:59 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:52:59 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:53:01 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:53:01 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:53:01 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:53:05 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:53:05 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:53:05 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:53:07 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]
May 22 06:53:07 mail postfix/submission/smtpd[21651]: lost connection after CONNECT from unknown[unknown]
May 22 06:53:07 mail postfix/submission/smtpd[21651]: disconnect from unknown[unknown]
May 22 06:53:11 mail postfix/submission/smtpd[21651]: connect from unknown[unknown]

请问大概有那些原因会造成这个问题