Address was not found, is unknown or is not receiving messages

Hello. I have a problem with my webmail. I use Horde (v 5.2.14), when I try to send an email I get the following error: "There was an error sending your message: Message could not be delivered - the adress was not found, is unknown or is not receiving messages ..." I check and the adress is correct.. I check my exim log and I found this message: "2018-07-23 11:02:48 1fhWjw-0007Wd-6C H=(myhosting.domain.com) [127.0.0.1]:36774 X=TLSv1.2:ECDHE-RSA-AES128-GVD-SHA256:128 CV=no F= A=dovecot_plain:myaccount@otherdomain.com rejected after DATA: host lookup failed (127.0.0.1 does not match any IP address for localhost)" I try to find my horde log but in /var/cpanel/horde/log there isn't exists. Could you help me? Thank you