We use DNS a lot in email, particularly for authentication, so diagnosing why DNS isn’t returning what we expect it to is a pretty common challenge. And DNS responses aren’t exactly the clearest thing to understand. There are two types of DNS server we need to know about. When we publish DNS records for our own domain we add them to a nameserver that is authoritative for our domain...
It’s time we talk about cold outreach mail. In the last 2 years the volume and aggressiveness of cold outreach mail seems to have exploded. There are dozens of companies out there who are selling services to companies to facilitate cold outreach. My own sales mailbox is full of requests from companies to help them solve their delivery problems. So let’s talk about cold outreach...
Why is designing spam filters like designing bear-proof trash cans?
Jody asks “Are ‘prefetch opens’ and ‘proxy opens’ the same thing?” Non-human opens An “open” is just someone (or something) fetching a remote image. A non-human-interaction (NHI) open is where some sort of automation fetches the image without human interaction – i.e. it’s fetched when the automation feels like it, not triggered by a user...
If you’re using sendy and you’ve found that RFC 8058 one click unsubscribe fails – or, worse, seems to work but doesn’t actually unsubscribe the user – you should take a look at James’ workaround.
Lots of times I see someone asking a question and they talk about their sending domain. And it’s sometimes not 100% clear which domain they mean by that – and when we’re talking about alignment and reputation it can make a difference. So here’s a list of (some of?) the different places a mailserver uses a domain. Hostnames Machine Hostname: What the operating system...
BIMI is the protocol you can use to publish an icon to display in the inbox of some large consumer webmail providers. To have it displayed at Gmail you need more than just clean DMARC and a published BIMI record, you also need to have a Verified Mark Certificate, a VMC. A VMC is a certificate, very similar in many ways to the TLS certificates used to secure webpages. It’s issued by a...
DMARC is the newest of the authentication protocols. It compares the domain in the From: address to the domains authenticated by SPF and DKIM. If either SPF or DKIM pass and they are in the same organizational domain as the domain in the From: address then the email is authenticated with DMARC. I wrote A Brief DMARC primer back in 2014 – when Yahoo deployed p=reject late on a Friday and...
The gentleman with the excellent hat is Иван IV Васильевич, The Great Sovereign, Tsar and Grand Prince of all Russia, Vladimir, Moscow, Novgorod, Tsar of Kazan, Tsar of Astrakhan, Sovereign of Pskov, Grand Prince of Smolensk, Tver, Yugorsk, Perm, Vyatka, Bolgar and others, Sovereign and Grand Prince of Novgorod of the Lower Land, Chernigov, Ryazan, Polotsk, Rostov, Yaroslavl, Beloozero, Livonia...
A common complaint about the advice or answers any deliverability person gives is that the generic answer to questions is: It Depends. This is frustrating for a lot of folks because they think they’re asking a simple question and so, clearly, there should be one, simple, clear answer. The problem is that there is almost never one answer in deliverability and details do matter. Let’s...
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