kumomta/docs/userguide/operation/performance.md

Performance Tuning

Operating System Tuning

The following tuning parameters can help KumoMTA fully leverage its host server resources.

These parameters should be added or updated in /etc/sysctl.conf:

vm.max_map_count = 768000
net.core.rmem_default = 32768
net.core.wmem_default = 32768
net.core.rmem_max = 262144
net.core.wmem_max = 262144
fs.file-max = 250000
net.ipv4.ip_local_port_range = 5000 63000
net.ipv4.tcp_tw_reuse = 1
kernel.shmmax = 68719476736
net.core.somaxconn = 1024
vm.nr_hugepages = 20
kernel.shmmni = 4096

After editing, the changes can be implemented without a restart with the sysctl -p command.