POSTFIX Won't Start says: bind 0.0.0.0 port 25: Address already in use

Solution 1:

It looks like you're trying to run different TLS certificates on different IP addresses. You have configured master.cf to answer the smtp and submission ports for specific IPv4 addresses with different TLS certificates.

But, you have also left in the original smtp line which, for some reason, is set to call postscreen. This line is triggering the error. It can't bind to INADDR_ANY because specific IP address listeners have already been bound. That is why you get the error Address already in use. And the reason you don't see anything in netstat or lsof output is because Postfix quits and the addresses are unbound.

You should comment that line out of master.cf.