Pernah mendapatkan pesan error seperti ini di smtp server anda?

Sep 6 11:00:08 vps-01 postfix/smtp[19191]: D4040D4074: enabling PIX workarounds: disable_esmtp delay_dotcrlf for mail.rootbox.or.id[202.154.57.62]:25
Sep 6 11:00:08 vps-01 postfix/smtp[19189]: C6B95D4077: to=, relay=mail.rootbox.or.id[202.154.57.62]:25, delay=1.9, delays=0.75/0/0.04/1.1, dsn=5.7.1, status=bounced (host mail.rootbox.or.id[202.154.57.62] said: 550 5.7.1 Requested action not taken: message refused (in reply to end of DATA command))
Sep 6 11:00:08 vps-01 postfix/qmgr[4641]: C6B95D4077: removed

Solusinya mudah, ada di http://www.postfix.org/postconf.5.html#smtp_pix_workarounds, anda cukup menambahkan

smtp_pix_workarounds = disable_esmtp delay_dotcrlf

di /etc/postfix/main.cf anda. Dan restart postfix anda.

--budiw