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...
I’ve been hearing a lot lately about DMARC. Being at M3AAWG has increased that. Last night we were at dinner and heard from the next table “And they’re not even publishing DMARC!!!!” I know DMARC is the future. I know folks are going to have to start publishing DMARC records. I also know that the protocol is the future. I am also not sure that most companies are ready for...
Dear Laura, I have a client moving from an external ESP to an internal system. They send approximately eight million messages per year, and these are primarily survey emails on behalf of their clients. We’ve had some conversations about authentication, and I’m trying to help them figure out if they just need DMARC or if they also need DKIM and SPF. It seems some ISPs prefer different methods, and...
I don’t always do predictions posts, even though they’re popular. Most years I skip them because I don’t see major changes in the email space. And, I’m not the type to just write a prediction post just to post a prediction. This year, though, I do see changes for everyone in the email space. Most of them center on finally having to deal with the technical debt that’s been accumulating over the...
Someone mentioned on a mailing list that mail “from” intuit.com was being filed in the gmail spam folder, with the warning “Our systems couldn’t verify that this message was really sent by intuit.com“. That warning means that Gmail thinks it may be phishing mail. Given they’re a well-known financial services organization, I’m sure there is a lot of...
I just saw a post over on the mailop mailing list where someone had been bitten by some of the IPv6 email issues I discussed a couple of months ago. They have dual-stack smarthosts – meaning that their smarthosts have both IPv4 and IPv6 addresses, and will choose one or the other to send mail over. Some domains they send to use Office 365 and opted-in to receiving mail over IPv6, so their...
One of the things we do for just about every new client coming into WttW is have them send us an email from their bulk mail system. We then check it for technical correctness. This includes things like reviewing all the different From headers, rDNS of the connecting IP, List-Unsubscribe headers and authentication. This is always useful, IMO, because we often find things that were right when they...
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 <<>>...
When the Domain Name System was designed thirty years ago the concept behind it was pretty simple. It’s mostly just a distributed database that lets you map hostname / query-type pairs to values. If you want to know the IP address of cnn.com, you look up {cnn.com, A} and get back a couple of IP addresses. If you want to know where to send mail for aol.com users, you look up {aol.com, MX}...
When emails are sent, there are two from fields, the Mail From and the Display From address. The Display From address (technically referred to as RFC.5322 from address) is the from address that is displayed to the end user within their email client. The Mail From (technically referred to as RFC.5321 from address) is the email address to which bounce messages are delivered. The Mail From field...
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