ISPConfig is the best platform I have ever seen, and re your question how far you should go: It is all fine, and nevertheless, re other companies:...
Should be true, but I have seen too many failures. Just my two cents, you can set to may or leave as is with dane if you want to go the extra mile...
That's true, security mechanism using dns and the tlsa record. Some have not configured correctly, and if you use dane you may leave mails on the...
Dane is an extra security using dnssec, and not all servers support it. If not configured correctly messages in/out will not be delivered because...
Thanks, that helped. Really appreciated.
If the error still exists, it may be helpful to replace "dane" in postfix and set to "may". Something like: sed -i -e 's/smtp_tls_security_level...
Separate names with a comma.