问题已解决,是smtp没有使用正确的端口导致的,刚安装好不能使用25端口发送邮件。

今天刚安装好的iredmail0.98是可以发送邮件,后来没去管它了,就出现错误:
/var/log/maillog错误如下:
SA-AES256-GCM-SHA384 (256/256 bits)
May 27 09:59:12 mx postfix/smtpd[2728]: NOQUEUE: reject: RCPT from unknown[112.10.45.233]: 504 5.5.2 <LS--20160802HHU>: Helo command rejected: need fully-qualified hostname; from=<dingxp@cgbuyu.com> to=<13735573961@139.com> proto=ESMTP helo=<LS--20160802HHU>
May 27 09:59:13 mx postfix/smtpd[2728]: disconnect from unknown[112.10.45.233]

vim /etc/postfix/main.cf里面 smtpd_helo_restrictions这一行删除reject_non_fqdn_helo_hostname,重启postfix后又报Helo command rejected Host not found错误,请大家帮忙看下是什么问题: