CategoryTechnical

SPF debugging

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...

Trawling through the junk folder

As a break from writing unit tests this morning I took a few minutes to go through my Mail.app junk folder, looking for false positives for mail delivered over the past six weeks. We don’t do any connection level rejection here, so any mail sent to me gets delivered somewhere. Anything that looks like malware gets dumped in one folder and never read, anything that scores a ridiculously high...

DMARC News – Gmail p=reject and ARC

DMARC.org announced this morning that Gmail will be moving to publishing a p=reject DMARC record in June of next year, much the same as Yahoo and AOL have. Unlike Yahoo and AOL, Gmail are giving those who will be affected plenty of time to prepare for any issues, and have waited until there are some potential ways to mitigate problems in the development pipeline. The ARC proposal, mentioned in...

IPv6 and authentication

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...

TXTing

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 <<>>...

A brief history of TXT Records

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}...

IPv6 Email is a little different

On Monday I talked about how big IPv6 address space is, and how many IPv6 addresses will be available to end users. We’re mostly an email blog, though, so what’s the relevance to sending email? If the recipient you’re sending to has an IPv6 mailserver you can send mail to them over IPv6, if you choose to. If they only have an IPv6 mailserver, with no IPv4 mailserver at all then...

IPv6 is big

IPv6 is big. Really big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist, but that’s just peanuts to IPv6. The old Internet, the one you’re probably using right now, runs on IP version 4. IPv4 addresses have numbers and dots; they look like 172.224.4.56. There are about 4,009,754,624...

Microsoft Send

Microsoft Send is a new mail client by Microsoft for iPhones and soon Windows Phone and Android phones. Send is designed to send quick, short messages to contacts. Instead of building a chat application build on a proprietary protocol, Send sends and receives its messages over email and uses your existing mailbox to handle the messages. What makes Send neat is that I can start a conversation...

Image Blocking

I received this email earlier this week, an email that I wanted but this is how it arrived. The email contained a single image link, a text line of who the message was sent to, the senders name, address, and finally an unsubscribe link. Good news, the email is CAN-SPAM compliant! Bad news, I have no idea what the content of the message is and it looks somewhat spammy.  The email was sent to my...

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