Transport Layer Security (TLS) is what gives you the little padlock in your browser bar. Some people still call it SSL, but TLS has been around for 18 years – it’s time to move on. TLS provides two things. One is encryption of traffic as it goes across the wire, the other is a cryptographic proof that you’re talking to the domain you think you’re talking to. The second...
It’s easy to tell if a domain is using SPF – look up the TXT record for the domain and see if any of them begin with “v=spf1”. If one does, they’re using SPF. If none do, they’re not. (If more than one does? They’re publishing invalid SPF.) AOL are publishing SPF. Geocities aren’t. For DKIM it’s harder, as a DKIM key isn’t published at a...
I’ve got multiple clients right now looking for insights about bounce handling. This means I’m doing a lot of thought work about bounces and what they mean and how they match up and how different ISPs manage delivery and how different ESPs manage delivery and how it all fits together. One thing I’ve been trying to do is contextualize bounces based on what the reason is. Despite...
Happy New Year! We’re looking forward to some interesting new projects this year, both for our clients and for Word to the Wise. Stay tuned! December was a slow month for blogging, with everything going on. But we’re back on the horse now and ready to blog for 2017. List and subscription management continue to be hot topics, especially in the wake of the listbombing attacks earlier this...
“What would you do for 25% more sales?” It’s panicked gift-buying season, and I got mail this morning from Boutique Academia, part of their final push before Christmas. They’re hoping for some Christmas sales in the next three days. They do make some lovely jewelry – ask Laura about her necklace some time – so I clicked on their mail. That’s not good. I...
Last week the megarbl.net domain name expired. Normally this would have no affect on anyone, but their domain registrar put in a wildcard DNS entry. Because of how DNSBLs work, this had the effect of causing every IP to be listed on the blocklist. The domain is now active and the listings due to the DNS wildcard are removed. How does a domain expiration lead to a DNSBL listing the whole internet...
Hurricane Electric had a significant outage of their authoritative DNS servers this morning, causing them to return valid responses with no results for all(?) queries. This will have caused delivery problems for any mail going to domains using HE.net DNS – which will include some of their colocation customers, as well as users of their free services – but also will have caused reverse...
There are so many things that need to happen to make the Internet work. DNS entries need to be right. MXs need to be set up. Web servers need to be configured. And, let’s be honest, anyone who has ever run their own services on the Internet has flubbed a configuration. We don’t think about it, because most of the time the configurations are handled by scripts and they do things right...
Some mechanisms and modifiers (collectively, “terms”) cause DNS queries at the time of evaluation, and some do not. The following terms cause DNS queries: the “include”, “a”, “mx”, “ptr”, and “exists” mechanisms, and the “redirect” modifier. SPF implementations MUST limit the total number of those terms to 10...
On Friday I talked a bit about the history behind TXT records, their uses and abuses. But what’s in a TXT record? How is it used? When and where should you use them? Here’s what you get if you query for the TXT records for exacttarget.com from a unix or OS X command line with dig exacttarget.com txt ~ ∙ dig exacttarget.com txt ; <<>> DiG 9.8.3-P1 <<>>...
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