1 Topic by wesley8086

  • wesley8086
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  • Registered: 2018-10-26
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Topic: Helo command rejected: Host not found

==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 0.9.8
- Linux/BSD distribution name and version:  CentOS 7
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro?
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I found following log in /var/log/maillog. It seems DNS is resolved, why it's REJECT?

Oct 26 08:04:05 mx postfix/smtpd[28657]: NOQUEUE: reject: RCPT from rn2-txn-msbadger05101.apple.com[17.111.110.85]: 450 4.7.1 <rn2-txn-msbadger05101.rno.apple.com>: Helo command rejected: Host not found; from=<do_not_reply@email.apple.com> to=<xxxx@xxx.cn> proto=ESMTP helo=<rn2-txn-msbadger05101.rno.apple.com>

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2 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
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  • Registered: 2009-05-06
  • Posts: 30,793

Re: Helo command rejected: Host not found

wesley8086 wrote:

Helo command rejected: Host not found; ... helo=<rn2-txn-msbadger05101.rno.apple.com>

because HELO hostname is not resolvable by DNS query (no A record).