Mail sent by form in site

My site is hosted on your servers, and i have a form for sending emails. However it is not possible to send any message because the the domain (sqgkuoew.epizy.com) is reported in various black lists. I performed a scan and found that beyond sqgkuoew.epizy.com and respective domain IP address (185.27.134.216) and also ip 185.27.134.22 is reported in multiple black lists. It is essential and urgent that the situation is resolved. I appreciate that you explain me how to resolve this insue.
Best regards.