Sometime in late 2024, a lot of SME marketers noticed something strange. Open rates started dropping. Click rates dropped with them. Nothing in the campaigns had really changed.
Then 2025 hit, and the trend got worse. Not slightly worse. Materially worse. The kind of drop where the marketing team starts having uncomfortable conversations with the commercial director.
If your numbers fell off a cliff and you've been blaming your subject lines, you can stop. The subject lines are probably fine.
In February 2024, Google and Yahoo brought in new bulk sender rules. They were quiet about it at first, but the practical effect was huge.
If you send more than 5,000 emails a day to Gmail addresses (which most B2C SMEs do, and a surprising number of B2Bs do too), you now have to:
The crucial bit is the engagement piece. Gmail and Yahoo are both now leaning much harder on engagement signals to decide where your emails go. Inbox or promotions tab. Promotions tab or spam. Spam or never delivered at all.
Nobody is going to tell you that this is happening. There's no warning email. You just notice that the open rate that used to be 24% is now 11%, and the click rate has dropped with it.
Across the audits I've run since the start of 2025, the same picture keeps appearing.
The interesting bit is that the businesses doing this badly aren't doing anything new. They're sending the same campaigns they sent in 2022. Same list. Same content. Same cadence. The world moved, and they didn't.
When I was at Goodwood, we cut email volume by 60% while increasing engagement, just by getting smarter about who got what and when. That same logic applies now, but with more urgency. Frequency without engagement is no longer just inefficient. It's actively damaging.
1. Check your DMARC record. If it's set to "none" or you haven't got one, that's job one. Set up SPF, DKIM and DMARC properly. Move DMARC from "none" to "quarantine" once you're confident the legitimate mail is authenticating. There are free tools (mxtoolbox, dmarcian) that will tell you exactly where you stand in 30 seconds.
2. Clean your list. Anyone who hasn't opened in 12 months is probably hurting your sender reputation. Suppress them, or run a reactivation campaign and then suppress those who don't respond. This will feel scary because you'll be removing thousands of names. The names that stay will engage at 2 to 3 times the rate of the average you had before. Your numbers will look better and so will your deliverability.
3. Segment by engagement. Send your most active people more, your least active people less. Stop blasting everyone the same thing. The simplest split: active (engaged in 30 days), warm (engaged in 31 to 90 days), and cold (no engagement in 90+ days). Send to actives often. Send to warm carefully. Reactivate cold or suppress them.
4. Warm new sending domains slowly. If you've migrated to a new ESP or domain, ramp up gradually over four to six weeks. Otherwise you'll torch your reputation in a fortnight and spend six months trying to recover it. This is the single most common mistake I see when companies switch platforms.
5. Look at where you're landing. Use a tool like Mail Tester or GlockApps to see if you're hitting inbox or promotions across major providers. Most SMEs have never checked. You can spend £20 once a quarter and have a much clearer picture of what's actually happening to your emails after they leave your ESP.
Email deliverability is not a fix-once project. It's an ongoing monitoring discipline.
The simplest version: every quarter, check your DMARC reports (your ESP or a tool like Postmark's free DMARC monitoring will surface them), run a deliverability test through Mail Tester or GlockApps, and review your engagement segments. If active subscribers are dropping or cold subscribers are growing, something needs attention.
Most SMEs will never put this discipline in place. The ones that do quietly outperform their competitors on email by a wide margin.
Email is still the highest ROI channel for almost every SME I've worked with. But the rules of the game have changed, and the businesses still treating it like 2018 are quietly bleeding revenue.
It's not glamorous work. Setting up DMARC isn't going to win anyone an award. But it might be the difference between a 22% open rate and a 9% one, and that gap is where your email programme either pays for itself ten times over or quietly dies in the promotions tab.
When was the last time you properly audited your sender reputation? If the honest answer is "never", that's where I'd start.