/usr/bin/rmail.postfix causes malformed from address.

Issue

• Application is using rmail to send emails but rmail appears to be causing problems with the from address when sending mail.
• Here are the /var/log/maillog entries after running 'rmail user@example.com < /etc/hosts':

Jan 10 07:54:04 host postfix/pickup[42009]: 5183821C5F: uid=107100 from=<localhost@>
Jan 10 07:54:04 host postfix/cleanup[44808]: 5183821C5F: message-id=<20140110155404.5183821C5F@example.com>
Jan 10 07:54:04 host postfix/qmgr[32429]: 5183821C5F: from=<localhost@>, size=382, nrcpt=1 (queue active)
Jan 10 07:54:04 host postfix/smtp[44810]: 5183821C5F: to=<user@example.com>, relay=relay.example.com[10.x.x.x]:25, delay=0.21, delays=0.04/0.01/0.14/0.03, dsn=5.1.3, status=bounced (host relay.example.com[10.16.232.31] said: 553 5.1.3 <localhost@>... Hostname required (in reply to MAIL FROM command))
Jan 10 07:54:04 host postfix/bounce[44811]: 5183821C5F: sender non-delivery notification: 8B34A21C79
Jan 10 07:54:04 host postfix/qmgr[32429]: 5183821C5F: removed