We have 25 domains on our Virtualmin.
This server receives email from only one external Antispam server (on a different network)
#1 - It seems that inbound email is being throttled since the Antispam server has the mail queued up as deferred by the Virtualmin server. How can we adjust these limits?
#2 - How can we set Postfix to accept mail ONLY from one or two IPs ?
Thank you.
You shouldn’t ask multiple questions, create a post per question.
As far as I know Virtuamin doesn’t have setting for that, you need to investigate Postfix settings.
What is the queue message on the Antispam server that says there is a limit. If there is a limit its probably done to stop overloading the server and crashing (ie. denial of service attacks) it so you must be sending alot of emails at one time.
Check the mail log file for a error/warning may tracking down what causing it.
Webmin postfix module it documented here. That may have a setting, its normally the postfix default.
Found this post
https://serverfault.com/questions/658156/limit-concurrent-connections-to-postfix-server
That seems unlikely. What does the log say about the situation?