How to curtail appetites of Postfix-a?

Question

System administration

The task, in principle, is this:
there is a forum on Vbulletin, periodically a couple of times a month a mailing list is made to users, according to a couple of paragraphs, no more, users under 7 thousand.
So - at the time of sending, the postfix loads the VPS to such an extent that the sites that hang on it stop responding, is there any way to reason with it?
Thanks to those who answered in advance

Answer 1

You can limit the number of postfix processes:
1st way - specify default_process_limit in main.cf - default is 100, try setting it to 50
2nd way - you can specify the limit of processes for each worker in master.cf, we are interested in: line
smtp unix - - - - - smtp
the penultimate column is the process limit of this worker
can be changed to
smtp unix - - - - 40 smtp
Restart postfix after any changes.

Answer 2

it is necessary to find out the bottleneck and add the resource
ps
7000 is nonsense for mailing lists. should be gone in a minute or two