Emails not sending and slow to receive

Emails not sending and slow to receive

We are receiving error messages like the one below to people we email often. We do not have anyone on the blocked list.

Also, emails are not arriving on time. When I refresh, emails pop up from hours earlier

Please advise.

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.

Tom.wood@cataler-na.com, ERROR_CODE :550, ERROR_CODE :permanent failure for one or more recipients ( tom.wood@cataler-na.com:blocked)



Received:from mail.zoho.com by mx.zohomail.com
    with SMTP id 1501094845117356.63494289904054; Wed, 26 Jul 2017 11:47:25 -0700 (PDT)
Message-ID:<15d80399a75.12b0b 5ea4350808.4832588305851426815@carringtoninc.com>
Date:Wed, 26 Jul 2017 14:47:25 -0400
From:Sharon McNeil < smcneil@carringtoninc.com>
User-Agent:Zoho Mail
To:"Tomwood" < Tom.wood@cataler-na.com>
Subject:Fwd: materials
Content-Type:multipart/mixed;
    boundary="----=_Part_1111747_1029086032.1501094845050"