Spam Resource: All Things Deliverability
I'm Al Iverson and I'm here to help. Got questions about email deliverability? You’ve come to the right place! For 25 years, I’ve been writing about email technology, sender requirements, authentication, spam prevention, and deliverability best practices. With over 2,000 articles in the archives, there’s plenty to explore. Can't find what you're looking for? Drop me a line with your question and I'll do my best to follow up. And don't forget to subscribe to the email newsletter to get fresh deliverability insights delivered straight to your inbox every week or two.
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Mailbox full: Not always an inbox problem

Mailbox full: Not always an inbox problem

When an email bounces back with a "mailbox full" or over-quota SMTP rejection, the standard assumption is that a subscriber has let thousands of unread messages pile up in their inbox. For Gmail users, that assumption might actually be wrong. As Mark Hachman points out in his PCWorld article, Your Gmail storage problem probably isn’t Gmail , Google uses a single pooled storage quota across Gmail, Google Drive, and Google Photos (and even mobile backups). A subscriber’s inbox could be now…

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Mailbox full: Not always an inbox problem

When an email bounces back with a "mailbox full" or over-quota SMTP rejection, the standard assumption is that a subscriber has let thousands of unread messages pile up in their inbox. For Gmail users, that assumption might actually be wrong. As Mark Hachman points ou…

Google Resurrects Its Verified Political Sender Program

Remember Google's program to verify US political senders? (Which Jennifer Nespola Lantz covered for Spam Resource back in 2022, see here and here to revisit that bit of history.) Well, it's back. The Gmail Verified (Political) Sender Program returns, re-launching Sept…

Apple Not Changing "Hide My Email" Addresses After All

In July, I reported that Apple planned to migrate domains for both iCloud Private Relay (Sign in with Apple) and "Hide My Email" over to a new shared domain: private.icloud.com. While existing legacy addresses were set to keep working, all newly generated addresses …

Having trouble adding users and domains in GPT V2?

Multiple folks have reached out asking why they're having trouble adding new domains or users in the new Google Postmaster Tools (GPT) V2 interface. In my own testing, adding domains and users generally does work, but with a few notable quirks. The primary issue is a UI ref…

I’m a DMARC fan. Are you?

Based on this totally scientific, absolutely guaranteed to be accurate poll that I ran on Linkedin for the past week or so, DMARC is almost universally loved. A couple of people got a bit snarky in the comments, pointing out the “social media effect” and that this was like ask…

GPT: V1 Retirement and Important Updates

Things are happening in the world of Google Postmaster Tools. If you’re a long time user of Google’s sender reputation dashboard known as Google Postmaster Tools ( what is that? ), you may have already seen the warning: As of October 31, the legacy version of Google Postmaster …

Ask Al: How do you actually set up a BIMI logo?

In previous videos, I’ve talked a lot about BIMI sender logos, often in the abstract. Many people do seem to understand what a BIMI logo is, by now. All well and good, but I did recently have somebody ask me, okay, well, I think I kind of get it, but how do you actually DO it. …

Email Isn't Dead, and Neither Is This Blog: Spam Resource at 25

When I published my very first post back in August 2001, I never envisioned that I'd still be sitting at a keyboard twenty-five years later talking about email deliverability. A quarter of a century. Twenty of those on Google's Blogger platform. That is an internet eter…

No Reply, Not Your Domain? Yes, Problem

As reported by Ars Technica , security researcher Cory Solovewicz owns the domains noreply.net and noreply.us. Every day, he sees nearly 700 inbound email attempts to addresses on those domains. That is a massive amount of misdirected mail, and it's leaking personally ident…

Fun with data: Progressive sender list breakdown

Here's a quick data snapshot that a friend was kind enough to share. The friend manages a smaller progressive sender email list, and he brought this out when we happened to be chatting about the new APRF feedback standard . Right now, Comcast is the only provider offering u…

Lukas Lunow: Why Does Microsoft Trash My Emails?

If you're living in the land of Salesforce Marketing Cloud and struggling when it comes to getting your emails reliably delivered to Microsoft inboxes, then this guide is for you. A longtime Salesforce consultant (and previously an expert solutions consultant for the Salesf…

You should hire: Jennifer Nespola Lantz

My friend, expert deliverability consultant, Jennifer Nespola Lantz , recently posted to Linkedin that the broad layoffs happening in tech right now have reached her. In her post , she writes: Hello everyone! I'm looking for work. Full-time, contract, consulting, and so on!…

Physician, heal thyself: Even I can get auth wrong!

Here is a fresh slice of humble pie: even after years of advising senders on authentication protocols and email best practices, I managed to break my own newsletter's SPF record last week. I try to practice what I preach. My newsletter list is 100% double opt-in, no spam he…

BIMI: What does self-asserted mean?

What does it mean when people talk about a "self-asserted" BIMI logo, and should you set one up? That's the topic of my latest Valimail "Ask Al" video. A standard BIMI record does two things. It publishes a link to an SVG file, which is the logo you wan…

The Context Box: Do It, But Right

Newsletter strategist Dylan Redekop recently wrote about the "context box, " his term for the line in a marketing or newsletter email explaining why you are receiving a particular message. (By the way, I think he coined something useful here, so I'm totally going …

Troubleshooting 554 5.7.5 DMARC-related SMTP rejections

It's a bit of a cryptic error message, isn't it? Mail bouncing back with "554 5.7.5 Permanent error evaluating DMARC policy." Wondering how to troubleshoot that? Well, I covered exactly this in a recent Ask Al video for Valimail, which was inspired by this Red…

Webinar Alert: From DKIM to DKIM2: What Senders Need to Know Now and What Mailbox Providers Expect

Hey, big senders! Are you unsure about DKIM2 and wondering what you need to know about it? If so, the Certified Senders Alliance (CSA) has got you covered, with a free webinar on this very topic upcoming on Tuesday, August 25th at 9:00 AM US Central Time. Presented by Sebast…

Guest Post: The Race to the Bottom Runs Straight Past the Inbox

Editor's note: Today I've invited a contribution from Jakub Olexa, CEO of Mailkit and Omnivery . Jakub's a good guy, part of the collaborative spirit that works together to protect the email ecosystem from within, and I was curious about and intrigued by what he…

APRF: A New Standard for Deliverability Feedback

There's a very exciting new proposed email specification making its way through the IETF, called APRF (Aggregate Performance Reporting). The individual draft specification comes from Alex Brotman of Comcast, Tom Corbett of Iterable, and Emil Gustafsson of Google. And Comcas…