==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 0.9.9
- Deployed with iRedMail Easy or the downloadable installer? installer
- Linux/BSD distribution name and version: Ubuntu 16.04 LTS
- 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 have a spam filtering service and know all of the IP's of my mx's, so they are whitelisted and I don't accept connections from anyone else.

I recently experienced an error where my server was returning 'all server ports busy'. I was only able to do a cursory glance around and did not notice anything unusual (number of connections, load, etc) and decided I needed mail flowing so I rebooted it (virtual instance) and all has been well since.

In the system logs, when the problem began, I first started seeing messages from postscreen:

postfix/postscreen[12865]: NOQUEUE: reject: CONNECT from [x.x.x.x]:33370: too many connections

This IP is one of my authorized mx's.

Shortly thereafter, I started getting this next:

postfix/postscreen[12865]: warning: timeout sending connection to service private/smtpd

and at this point, it seems, is when postfix began returning 'all server ports busy' to my spamfilter mx's.

Rebooting the instance fixed the issue and there has not been a recurrence in a few hours. I have dug thru the logs and the only other abnormal thing happening was that there was a compromised user account that was receiving many smtp submission attempts from a zombie botnet all trying to deliver malware but getting shut down due to throttlings (50/hour). But I don't see the connection really because these are two entirely different activities. And, as I said, netstat -an did not show huge numbers of current or waiting connections. So bottom line is, what could possibly cause postscreen to blow up? I don't think it depends on a whole lot external to itself (database and etc).

I am considering removing postscreen alltogether since my spamfiltering gateways are the only smtp hosts I talk smtp to directly anyways. Still however if there is a postscreen bug this would be good to follow up on for the sake of others.

Mike-