I’d been having trouble sending to a mailing list which I read. The mails weren’t bounced back; they simply vanished into the ether. My domain publishes SPF records but these allow my colocated server and my home network to send mail.

But what they don’t allow … is the colo server’s upstream relay.

Oops.

Luckily GoDaddy – for it is they – publish a dedicated SPF record which I could easily include in my own details. I was then able to post to the mailing list.

I began to wonder how many other emails I might have sent out but which simply vanished. Then I remembered that these particular ones were all being sent via the colo server. Usually I send mail directly from my home network so I would have been OK.