Mail issues 544 error from spamhaus? blacklisted IP?

I have mail hosted on zoho (@pluswancomms.com)

but when trying to send email to @capellahotelgroup.com I get the following error

Invalid Address, ERROR_CODE :554, ERROR_CODE :Service unavailable; Client host [ sender1.zohomail.com ] blocked by zen.spamhaus.org ; 74.201.84.162