why exim server reject email from a specific domain

Please help me to fix this issue withe exim mail server exim mail server rejects emails from the following domaine 2016-04-29 11:05:20 H=infastmail-02-saas.austin.hp.com [15.224.192.102]:49180 temporarily rejected connection in "connect" ACL: "Host is ratelimited (1.3/1h max:1.2)" 2016-04-29 11:38:45 H=infastmail-02-saas.austin.hp.com [15.224.192.102]:33131 temporarily rejected connection in "connect" ACL: "Host is ratelimited (2.8/1h max:1.2)" 2016-04-29 12:12:01 H=infastmail-02-saas.austin.hp.com [15.224.192.102]:36499 temporarily rejected connection in "connect" ACL: "Host is ratelimited (1.6/1h max:1.2)" 2016-04-29 12:28:40 H=infastmail-02-saas.austin.hp.com [15.224.192.102]:36798 temporarily rejected connection in "connect" ACL: "Host is ratelimited (1.2/1h max:1.2)" 2016-04-29 12:45:21 H=infastmail-02-saas.austin.hp.com [15.224.192.102]:54301 temporarily rejected connection in "connect" ACL: "Host is ratelimited (1.4/1h max:1.2)" 2016-04-29 12:45:22 H=infastmail-02-saas.austin.hp.com [15.224.192.102]:54309 temporarily rejected connection in "connect" ACL: "Host is ratelimited (1.4/1h max:1.2)" 2016-04-29 12:49:54 H=infastmail-02-saas.aus