Ensure postfix has a default hostname

Author: cytopia

Dockerfiles/prod/data/docker-entrypoint.d/301-postfix.sh

@@ -88,6 +88,7 @@ set_postfix() {
 
 		# Postfix catch-all
 		if [ "${enable_mail}" = "2" ]; then
+			run "postconf -e 'myhostname=php'" "${debug}"
 			run "postconf -e 'virtual_alias_maps=pcre:/etc/postfix/virtual'" "${debug}"
 			run "echo '/.*@.*/ ${username}' >> /etc/postfix/virtual" "${debug}"
 			run "newaliases" "${debug}"