Solusi atas error
Mar 6 09:42:15 mail postfix/smtp[22970]: DE3E43CC63: to=<nama.user@jaranguda.com>, relay=none, delay=0.07, delays=0.06/0.01/0/0, dsn=5.4.6, status=bounced (mail for imel.jaranguda.com loops back to myself)
tambahkan imel.jaranguda.com di mydestination /etc/postfix/main.cf
mydestination = localhost, localhost.localdomain, imel.jaranguda.com
ganti imel.jaranguda.com, dengan subdomain anda.
Setelah mengedit file diatas, reload service postfix anda.
service postfix reload
# atau
service postfix restart