cannot send email to sina/yahoo

[koolokamba]

problem 1:
cannot send email to sina.com via outlook, but send email to them via webmail is ok.

/var/log/zimbra.log
Jun 20 14:44:22 linjun postfix/smtp[18562]: DB42B2806D5: to=<koolokamba@sina.com>, relay=freemx2.sinamail.sina.com.cn[202.108.3.231], delay=238, status=deferred (host freemx2.sinamail.sina.com.cn[202.108.3.231] said: 450 4.7.1 Client host rejected: cannot find your hostname, [88.888.88.88] (in reply to RCPT TO command))


problem 2:
cannot send email to some domain via outlook, but send email to them via internal network is ok.

/var/log/zimbra.log
20.192.52.35]: 554 <t.kozuka@hayatele.co.jp>: Relay access denied; from=<zimbra@zimbra.com.cn> to=<t.kozuka@hayatele.co.jp> proto=ESMTP helo=<gz180>

[KevinH]

These may be related. Doesn't look like you have reverse DNS setup for the hostname. Have you tried setting up a relay host to your ISP?

[koolokamba]

your suggestion for problem 1 is ok.

but the problem 2...