Spam Resource: All Things Deliverability

It's time to define another email technology-related term for the DELIVTERMS series here on Spam Resource. Today, what we'll explain is SMTP AUTH, short for Simple Mail …

Hey, remember when I told you that V1 of Google Postmaster Tools was going away? Not so fast... Turns out Google has changed its mind, at least for now. Fellow deliverability exp…

Here's a confusing rejection that an email sender asked me about the other day. It's a Microsoft OLC (Outlook Consumer, aka Hotmail or Outlook.com) rejection, authenticat…

As of November 3, 2025, Google has added a new warning to their Bulk Sender Guidelines FAQ page, warning that enforcement "ramps up" beginning this month. The warning:…

In my last post , I talked about what DMARC doesn't do. What it cannot do, addressing limitations and mis-assumptions. But, as I said then, I am a DMARC fan. I don't thin…

Let me be clear. I am pro-DMARC. I think you should implement DMARC. It is a valuable part of email security best practices. But I want to be "eyes wide open" about it.…

Are you trying to send email and seeing it rejected with "Domain of sender address does not resolve" or "Unresolvable RFC.5321 or RFC.5322 from domain"? These…

Hey, retailers! Webinar alert. Retail email: a prime target for phishing and spoofing, with fake emails and fake receipts. Whether they be somebody spoofing your brand to sell kn…

Hey, on the one hand, I am genuinely surprised this question still pops up in 2025. But I get it. Every day, someone is new to this whole email thing, and they haven't yet na…

In his latest post, Brian Krebs reports on the exploit-of-the-week that's not really an exploit, depending on how you look at it. This time around, the bad guys are targetin…

I'm a big fan of Civic Shout , a platform that helps individuals and progressive nonprofits find and connect with supporters to champion their mission to improve the world ar…

Yahoo has long had a very useful portal for email senders, chock full of important information, known as the Yahoo Sender Hub . It's where savvy email senders go when trouble…

When you look at an email message in your Gmail spam folder, Google helpfully displays a little bit of text along the top of the message, telling you why they've delivered th…

For my latest Valimail video, I tackle something I don't think gets enough attention: how to secure your parked (non-mail-enabled) domains from spoofing and phishing. A Reddi…

Microsoft's SNDS (aka their Smart Network Data Services email reputation data portal) has recently undergone some minor updates that might impact your use of the platform, d…