hello,
mail server not recieving mail from Gmail , and I fixed it by run those commands :
mkdir /etc/ssl/private/
openssl req -new -x509 -days 3650 -nodes -out /etc/ssl/certs/dovecot.pem -keyout /etc/ssl/private/dovecot.pem
chmod o= /etc/ssl/private/dovecot.pem
openssl req -new -x509 -days 3650 -nodes -out /etc/ssl/certs/postfix.pem -keyout /etc/ssl/private/postfix.pem
chmod o= /etc/ssl/private/postfix.pem
postconf -e smtpd_tls_cert_file=/etc/ssl/certs/postfix.pem
postconf -e smtpd_tls_key_file=/etc/ssl/private/postfix.pem
service dovecot restart
service postfix restart
please fix it in the next aapanel update .