1 Topic by binhnd

  • binhnd
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  • Registered: 2019-06-19
  • Posts: 2

Topic: Why Postfix can Block client IP with Iptables

==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): iredmail 0.9.5
- Deployed with iRedMail Easy or the downloadable installer?
- Linux/BSD distribution name and version: Ubuntu 16.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): mysql
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? no
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

Hi everyone,

I have an issue with my mail system that i can't find solution for that.
The issue that: my mail server auto add iptables rule to block a client ip.
I don't use ufw, fail2ban or any service that trigger iptables.
When i check mail.log i see:
postfix/smtpd[27057]: NOQUEUE: reject: RCPT from xxxxxxx[yyyyyyy]: 550 5.1.1 <aaa@bbb.com>: Recipient address rejected: User unknown in virtual mailbox table; from=<ccc@bbb.com> to=<aaa@bbb.com> proto=ESMTP helo=<xxxxxxxxxx>

And i guess postfix can block the client ip yyyyyyy with iptables. But i can't find any information that, postfix can do that.

Anyone here have the same problem and have an idea to resolve that.

Thanks so much!

----

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2 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
  • iRedMail Developers
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  • Registered: 2009-05-06
  • Posts: 30,792

Re: Why Postfix can Block client IP with Iptables

binhnd wrote:

Recipient address rejected: User unknown in virtual mailbox table

This log means the recipient address doesn't exist on your server, so Postfix rejects it. This is normal and correct. And this doesn't mean the client is blocked in firewall.

3 Reply by binhnd

  • binhnd
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  • Registered: 2019-06-19
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Re: Why Postfix can Block client IP with Iptables

ZhangHuangbin wrote:
binhnd wrote:

Recipient address rejected: User unknown in virtual mailbox table

This log means the recipient address doesn't exist on your server, so Postfix rejects it. This is normal and correct. And this doesn't mean the client is blocked in firewall.

Thanks for your reply,
I know that log is normal. But the issue is that i see the client IP in this log is block by iptables rule after that.

Do you have any idea?

4 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
  • iRedMail Developers
  • Offline
  • Registered: 2009-05-06
  • Posts: 30,792

Re: Why Postfix can Block client IP with Iptables

binhnd wrote:

I know that log is normal. But the issue is that i see the client IP in this log is block by iptables rule after that.

This is not expected. As you mentioned in first post, "I don't use ufw, fail2ban or any service that trigger iptables." Only Fail2ban will trigger the ban in iptables, not Postfix itself.