ISPManager 6 - R=dnslookup T=remote smtp defer (-53): retry time not reached for any host for

ISPManager 6 - R=dnslookup T=remote smtp defer (-53): retry time not reached for any host for

Ошибки при отправке почты со скрипта:

R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host for 'bitrixsoft.com'
R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host for 'rambler.ru'
R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host for 'gmail.com'
R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host for 'gmail.com'
R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host for 'email.ua'
R=dnslookup T=remote_smtp defer (-53): retry time not reached for any host for 'ukr.net'

в большинстве случаев означает блокировку 25 порта со стороны хостинг провайдера.