This is how I update my certificate, have to do it every 3 months though as I havent spent time to automate it.
Im running on Windows 10, so I got the Linux kernel service installed, with ubuntu image from the microsoft store, that gives me access to bash.
I use https://www.sslforfree.com/ for my certificate.
Open bash
Run:
sudo su -> username/password
openssl rsa -in “/mnt/c/temp/Axigen Certificate/private.key” -out “/mnt/c/temp/Axigen Certificate/Norlig.key”
cat “/mnt/c/temp/Axigen Certificate/Norlig.key” “/mnt/c/temp/Axigen Certificate/certificate.crt” > “/mnt/c/temp/Axigen Certificate/Norlig.pem”
cat “/mnt/c/temp/Axigen Certificate/Norlig.key” “/mnt/c/temp/Axigen Certificate/ca_bundle.crt” > “/mnt/c/temp/Axigen Certificate/ca_Norlig.pem”
Copy everything from ----Begin Certificate---- XXX to and including ----End Certificate---- from “ca_Norlig.pem” , to the end of Norlig.pem.
(everything except the RSA key…)
Copy Norlig.pem to: C:\Program1\Axigen Mail Server\certs , restart axigen mail service
In the listeners, I set the certificate to “certs/Norlig.pem”
hope this helps