It's 2024, PKI best practices are well known and well documented, anybody still using a self-signed certs on their mail server (or anywhere) is either lazy or stupid.
Plenty of existing applications will refuse to connect to a self-signed certificate on the belief that allowing the end-user to confirm a certificate offers basically 0 protection against malicious actors.
Plenty of existing applications will refuse to connect to a self-signed certificate on the belief that allowing the end-user to confirm a certificate offers basically 0 protection against malicious actors.