SMTP data timeout

[karming44]

My server is keeping received SMTP data timeout response from some companies who are trying to send me a email. [On the other hand, I can receive email from others normally] Any one can help??? THZ!!

SMTP data timeout (message abandoned) on connection from (smtpproxy11.qq.com) [183.62.126.xxx] F=<sender email>

SMTP data timeout (message abandoned) on connection from corp.forptr.21cn.com (corp.xxx.com) [121.14.129.xxx] F=<sender email>

SMTP data timeout (message abandoned) on connection from xxx.senderdomain.com [222.66.55.xxx] F=<sender email>

SMTP data timeout (message abandoned) on connection from xxx.senderdomain.com [211.151.62.xxx] F=<sender email>

SMTP connection from dmd73.mail85.dmdelivery.com [61.147.85.xxx] lost while reading message data (header)