Error sending the message.
A secure connection to this node could not be established: the requested domain name does not match the one specified in the server certificate.
Configuration related to mail.server.com , should be fixed.
edit the mail domain in hestia, tick the checkbox for ssl and lets encrypt and go to save. Be sure webmail.domain.com and mail.domain.com a records exists before doing this. Then use mail.domain.com to receive and send mails over ssl.
Error sending the message. A secure connection to this node could not be established: the requested domain name does not match the one specified in the server certificate.