Deliverability
Welcome to The Bounce House, a recurring monthly-ish series where I, Alison, your Deliverability BFF and inbox gossip queen, take on hot topics in the email world and scream what others will only whisper. This is where I talk about the good, the bad, and the confusing, because frankly, a lot of deliverability advice out there adds more confusion than clarity.
In this post, we’re zooming in on Gmail and cracking open a deceptively complex concept that’s taken center stage since Yahoo, Outlook, and Google tightened up their sender requirements in recent years:
Just make it easy to unsubscribe.
Sure. Sounds reasonable. But what if your idea of “easy” isn’t the same as Gmail’s?
It’s time to go back to school and re-learn unsubscribes, and for some email senders, that may mean getting called to the principal’s office, aka Gmail’s compliance dashboard. If you’ve been there lately, you may have seen a big, honking ❌ next to “One-Click Unsubscribe” or a nudge about honoring opt-outs. Consider this your detention.
Ok, so now that you’re officially in trouble, we need to correct the situation before this issue ends up on your permanent record.
Deciphering what Gmail actually means is harder than it looks! There have been countless Slack threads and blog posts debating what’s happening behind the scenes when these warnings are triggered.
Some senders assume Gmail’s warning means a broken or missing header. And sure, that could be the case. If you see either of these in your dashboard, start with the basics:
If all of that checks out, it gets trickier.
If you’re using the list-unsubscribe header, recipients might click Spam in Gmail, get the “Report spam or unsubscribe?” prompt, and choose to unsubscribe. If they click unsubscribe at that stage and backtrack on the complaint, Gmail could still interpret that as a negative engagement signal, even if you ultimately honor the opt-out. All signals are useful, and even a rescinded complaint could potentially carry some residual weight.
If the user does report you as spam, it’s a guaranteed reputation hit, and you’ll never know about it. Gmail doesn’t offer a traditional feedback loop (FBL), so there’s no complaint recorded, no unsubscribe triggered, no way to suppress future sends. They won’t even give you a complaint rate in Postmaster Tools if your volume or reputation isn’t high enough. Instead, they start filtering your mail to the spam folder, where engagement goes to die. In the spam folder, images stay un-fetched, meaning an open event never fires unless the recipient clicks “Report not spam.”
When Gmail sees you continue mailing someone who hit “spam,” (which is inevitable since you don’t know who they are) they know there are a few possibilities:
And then the dashboard throws a flag.
To me, Gmail’s warnings feel like a polite cover story. A genteel way of saying:
“You’re generating complaints. Knock it off. We’ll chalk this up to a header error unless proven otherwise.”
It’s well-meaning. But it’s also vague. If your headers are flawless and your system works, then the unsub warning might actually be your first sign of a deeper issue: users don’t want your emails anymore, and you’re not noticing.
The header is easy to fix. The complaints? Not so much.
When subscribers report mail as spam, they’re letting you know that they didn’t sign up, can’t opt out, or don’t like the content. You’ll need to use your own historical engagement data and deep knowledge of your customers to determine next steps, whether that’s overhauling your subscription process, changing your engagement criteria, modifying your cadence, or revamping your content.
Now that we’ve got that excitement out of the way, let’s talk headers.
Using a mailto: or https: link in your List-Unsubscribe header is step one for any competent sender. But Gmail won’t show the UI link unless it complies with RFC 8058, a quiet little spec that toiled in obscurity until the Great Yahoogling of 2024 made it mandatory. As a reminder, here’s a quick visual rundown of the updated sender guidelines for the four biggest inbox providers in the biz:
| Requirement | Gmail | Yahoo | Microsoft | Apple (iCloud) |
| SPF | ✅ | ✅ | ✅ (bulk only) | ✅ (bulk only) |
| DKIM | ✅ | ✅ | ✅ (bulk only) | ✅ (bulk only) |
| DMARC policy (p=none min) | ✅ (bulk) | ✅ (bulk) | ✅ (bulk) | ✅ (bulk) |
| DMARC alignment | ✅ (bulk) | ⚠️ Relaxed required (bulk) | ✅ Preferred (bulk) | ❓ Not specified |
| Valid FWD & REV DNS (PTR) | ✅ | ✅ | ✅ Required (on server) | ✅ Required (bulk only) |
| TLS Encryption | ✅ | ❌ | ❌ | ❓ |
| One-Click Unsubscribe | ✅ RFC 8058 | ✅ RFC 8058 | ✅ Visible link required | ✅ Visible option required |
| List-Unsubscribe Header | ✅ | ✅ | ❓ | ✅ (bulk only) |
| Unsubscribe Processing Timeline | ❓ | ✅ Within 2 days | ❓ | ✅ Immediately |
| Valid “From”/”Reply-To” | ✅ | ✅ | ✅ (bulk only) | ✅ (bulk only) |
| Bounce Handling / List Hygiene | ✅ | ⚠️ | ⚠️ | ✅ |
| Spam Complaint Rate | ✅ <0.10% ideal, avoid >0.30% | ⚠️ Keep low | ❓ | ❓ |
Legend:
RFC 8058 expects, among other things:
In other words, Gmail’s UI unsubscribe feature only shows up if you follow every rule, and have a healthy reputation.
It’s easy to mess up. If your ESP doesn’t implement RFC 8058 correctly, or if you’re missing a piece, you might be noncompliant and get flagged for user complaints, even when everything “looks fine.”
So when Gmail says:
“You might be noncompliant,”
what they mean is:
“Something’s off, and your complaint rate’s not helping.”
Just when you thought List-Unsubscribe headers couldn’t get more thrilling, Gmail launched a new “Manage Subscriptions” tab.
This inbox feature lists senders with List-Unsubscribe headers and shows:
It’s a mass opt-out dashboard, and a harsh reality check for over-eager marketers.
Naturally, this sparked panic. Some asked: Should we even use List-Unsubscribe if it exposes us like this?
My answer: abso-GOOT-ely™.
Gmail’s trying to empower users to manage their inboxes. If that feels like sabotage, keep gazing, because this tab isn’t a monster that gobbles your list; it’s a mirror, reflecting your own practices back to you.
If you’re worried users will see “20+ emails recently” and unsubscribe, don’t hide the exit. Raise your barrier for entry.
Blame the frequency.
Blame the boring content.
Blame the fact that not all 20+ of those emails were worth sending.
Then do better.
When Gmail users are unsubscribing or hitting spam and you never hear about it, your engagement data lies. You’ll think people are engaged because they opened a message. But they’re disengaging quietly or actively sabotaging your sender reputation.
This is how marketers get blocked or bulked while “following best practices.” It’s why “send to engaged users” is dangerously vague. Engagement goes beyond being present, it’s overwhelmingly positive signal strength. And even a spam complaint you don’t see still counts against you.
Support both mailto: and https: if possible. Mailgun does this by default—check with your ESP for their recommended implementation (or switch to us).
No cookies, no tracking, no sketchy business.
Does the link display? Where does it go? Does it feel safe and seamless?
High spam reports with low unsub rates = red flag. Check Google Postmaster Tools and dig into why people are being drawn to the “spam” button rather than unsubscribing.
Don’t just rely on opens. Look for behavior that shows delight, not just delivery.
Just as we were putting the final touches on this post, Gmail announced yet another Promotions tab glow-up, and marketers…you might want to sit down for this one.
Starting in the next few weeks, Gmail will begin ranking promotional emails by relevance rather than recency, at least in mobile Gmail apps for personal accounts. That means your beautifully timed campaign might get elbowed out of the top slot by an older, but more enticing, offer, depending on the user’s past interactions.
In other words: your email is no longer racing the clock: it’s up against the user’s brain chemistry.
Let’s call it what it is: this isn’t about open rates. It’s about clicks, conversions, and contextual cues.
How well do you actually understand your audience? Did they buy something similar before? Did they click last week’s offer? Did they open… and then hit spam? How long would it take you to figure out if they did?
Relevance to you (“But it’s our semi-annual flash sale!”) doesn’t mean relevance to them (“I already bought candles last week, y’all. 12 of them. What did you do with the money I just gave you?”)
Your inbox placement in Gmail’s Promotions tab is no longer just about getting in, it’s about where you land once you’re there.
We haven’t seen new developer specs for these latest Gmail features, but if history tells us anything (annotations, anyone?), structure matters.
If Gmail misinterprets your deal, highlights the wrong promo, or buries your best offer, that’s your problem, not theirs.
So, test. On mobile. In Gmail. With real content.
And if you’re trying to get that sweet placement in the Purchases view, double check that Gmail is actually recognizing your order confirmation and shipping dates. Otherwise, your customer might get notified that their newest package arrives… last Tuesday.
Also, heads up: the Purchases view only exists in personal Gmail accounts. So if you use your work email to track your Sephora splurges… first of all, same. But second of all, don’t expect this feature to follow you there.
So yes, send your flash sales. Your fall refresh. Your “last chance to save 30% before the full moon rises” campaign. But if they’re not tailored to the individual, useful, timely, and respectful of inbox real estate, Gmail is going to show someone else’s email first.
Worried? Curious? Ready to scream?
You know where to find me.
I’ll be bouncing.
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