ERROR_CODE :554, ERROR_CODE

ERROR_CODE :554, ERROR_CODE

Please solve soon my problem.
It is very important.

We get always this error:

This message was created automatically by mail delivery software.
 A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. 

marco@xxxxxxx.com, ERROR_CODE :554, ERROR_CODE :mxcmd04.ad.aruba.it bizsmtp ivqM1v00c0UKuXz01 Connection refused from 31.186.226.21. See http://csi.cloudmark.com/reset-request/?ip=31.186.226.21 for more information.



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 Message-ID:<003801d2f952$2ca26380$85e72a80$@fcserv.it>
 Date:Mon, 10 Jul 2017 09:57:27 +0200
 From:"amministrazione_FCSERVICE" <amministrazione@fcserv.it>
 To:"'Marco Quieti'" <marco@xxxxxxxxxx.com>
 Subject:I: rif.3788
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