Is there an issue with wildcard certs and TLS?
user@app01:~$ openssl s_client -connect splaam.domain.com.au:26 -starttls smtp -no_ssl3
CONNECTED(00000005)
depth=0 OU = Proxmox Mail Gateway, O = domain.com.au, CN = *.domain.com.au
verify error:num=18:self signed certificate
verify return:1...