On 2/26/21 12:10 PM, borg@uu3.net wrote:
Hmm right... Somehow I tought that having that special Null MX will silently discard message... I dont know why...
It's Friday. I'm presuming that many of us have had a long week and are ready for the weekend. ;-)
So, RFC 7505 is pretty much even pointless in my opinion.
No, it's not pointless. See Alan's reply to my previous message for why a Null MX helps as a sender / MSA operator. See point #2 in my previous message for why you care about Null MX as a receiver.
You have to do more.. to pretty much achieve the same.
But it's not the same. You cause hard failures fast. It means that sending servers should never contact the A / AAAA addresses, much less every time the sending system retries to send. So you do save yourself some CPU cycles as a recipient.
Its just easier to not having MX on subdomains that does not serve as email destinations.. Less records in DNS.
Easier has seldom been better. If you publish a Null MX for said subdomain(s), my server will give up immediately. If you don't publish a Null MX, my server will pester your A / AAAA IPs every four hours for days at a time. -- Grant. . . . unix || die