Postfix rejecting mail from authenticated clients

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http://serverfault.com – I am trying to configure Postfix so that it would accept mail from authenticated clients outside $mynetworks. When I try to send a test email from my iPhone, which is configured to use port 25, SSL and password authentication, the mail gets rejected by Postfix. I get the following in /var/log/mail.info: Oct 25 17:41:35 mailhost postfix/smtpd[6136]: warning: 212.183.x.x: hostname host212-183-x-x.uk.access.vodafone.net verification failed: Name or service not known Oct 25 17:41:35 mailhost postfix/smtpd[6136]: connect from unknown[212.183.x.x] Oct 25 17:41:39 mailhost post (HowTos)