Despite what a lot of SEO slop will try and tell you there’s no way to measure deliverability performance across multiple ESPs in any way that’s meaningful. (The SEO slop tends to do things like sign up for free accounts at a bunch of ESPs, send three emails to probe accounts and see how many reach the inbox at mailbox providers served by the probe account service. If you’re a...
Don’t add your domain to the Public Suffix List
Adding your domain to the public suffix list might break all your email.
Diagnosing Hard Bounces
A very short post about diagnosing hard bounces, because I’ve had to give the same advice to a dozen folks over the past few months. When you’re diagnosing and mitigating hard bounce rates the first thing you’ll see is your ESPs dashboard or reporting. It’ll tell you how many emails you sent bounced, and how that number has changed over time. A useful start. But a hard...
Stop using Entrust for your BIMI Certificates
You should probably stop using Encert for BIMI certificates. Apple definitely think you should.
Tracking link maths
How long does a tracking link need to be? Let’s make it interesting, and say we want to be able to have a unique tracking link for every single atom in the observable universe. That’s about 1080 unique links. One hundred novemdecillion exa-links. 100,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 If we have that many customers...
There’s text and then there’s text
If you want to send someone an email with some text in it there are quite a few different ways you can do it. The main differences are the ways the text is packaged up in MIME entities to be sent. text/plain This is the simplest sort of text you can send. If you send a simple email with many desktop mail clients, this is what you get. You can’t include images, you can’t choose fonts...
Your bounce classification is a bit rubbish
When a mailbox provider rejects or defers an email it sends back a message explaining why. Those messages begin with a three digit number (starting with a “5” for rejections and a “4” for deferrals), followed by text that explains why the mail wasn’t accepted. That text often contains a link to follow for more information, or a mailbox provider specific code you can...
Do we care about SPF alignment?
Do we really care whether our SPF email authentication is aligned?
Comparing DKIM keys
Sometimes we have a client who has done something wrong when setting up authentication. Their DKIM signing fails due to something being wrong with the public key they’ve published. The published key looks fine, by eye. It’s got all the fields it should have, but diagnostic tools give inscrutable error messages. If you’re lucky, “This doesn’t seem to be a valid RSA...
No, Gmail did not just break all open tracking
I was avoiding commenting on the email open tracking bad take that seems to be going viral round the more gullible corners of LinkedIn.
I avoided it for long enough that other folks wrote articles saying pretty much what I’d say. Yay!
You should read what Al has to say over at SpamResource.