any one experience a bounce email externally? I able to configure and install iredmail on afresh installed centos 6.2.

I could able to send email internally. but when send email external email address such as gmail email account it bounces.

by the way I am using a dyndns domain with a MX hostname.

here is the logs:

[root@imap postfix]# tail -f /var/log/maillog
Aug 24 23:57:49 imap postfix/qmgr[4569]: D73012C09D7: removed
Aug 24 23:57:51 imap postfix/smtp[4853]: 164FC2C09DA: to=<zepvil@gmail.com>, rel                                 ay=gmail-smtp-in.l.google.com[74.125.127.26]:25, delay=1.9, delays=0.11/0.05/0.5                                 4/1.2, dsn=5.7.1, status=bounced (host gmail-smtp-in.l.google.com[74.125.127.26]                                  said: 550-5.7.1 [203.117.153.247] The IP you're using to send mail is not autho                                 rized 550-5.7.1 to send email directly to our servers. Please use the SMTP relay                                  at 550-5.7.1 your service provider instead. Learn more at 550 5.7.1 http://supp                                 ort.google.com/mail/bin/answer.py?answer=10336 sb7si17141314pbc.1 (in reply to e                                 nd of DATA command))
Aug 24 23:57:51 imap postfix/cleanup[4839]: 087AE2C09DB: message-id=<20120824155                                 751.087AE2C09DB@av8.serveftp.net>
Aug 24 23:57:51 imap postfix/bounce[4861]: 164FC2C09DA: sender non-delivery noti                                 fication: 087AE2C09DB
Aug 24 23:57:51 imap postfix/qmgr[4569]: 087AE2C09DB: from=<>, size=3570, nrcpt=                                 1 (queue active)
Aug 24 23:57:51 imap postfix/trivial-rewrite[4827]: warning: do not list domain                                  av8.serveftp.net in BOTH mydestination and virtual_alias_domains
Aug 24 23:57:51 imap postfix/trivial-rewrite[4827]: warning: do not list domain                                  av8.serveftp.net in BOTH mydestination and virtual_mailbox_domains
Aug 24 23:57:51 imap postfix/qmgr[4569]: 164FC2C09DA: removed
Aug 24 23:57:51 imap postfix/pipe[4862]: 087AE2C09DB: to=<zeppy@av8.serveftp.net                                 >, relay=dovecot, delay=0.25, delays=0.04/0.03/0/0.18, dsn=2.0.0, status=sent (d                                 elivered via dovecot service)
Aug 24 23:57:51 imap postfix/qmgr[4569]: 087AE2C09DB: removed

^C
[root@imap postfix]#