Latest / Marketing Automation with Fexingo: HubSpot, Marketo, and Automated Customer Journeys / Why Your Abandoned Cart Emails Are Going to Spam
Transcript
- Lucas: There is a quiet disaster happening inside a lot of marketing automation platforms right now, and most teams won't notice until their next quarterly review. It's about abandoned cart emails — specifically, why they're increasingly landing in the spam folder. Luna: I've seen this with a few clients. One saw open rates fall from 45% to under 7% in about a month. But they didn't change a thing in the email itself. Lucas: Right — that's the scary part. The content stayed the same. What changed was how the receiving mail servers — Gmail, Outlook, Yahoo — started grouping and scoring those emails. And abandoned cart sequences are uniquely vulnerable. Luna: Because they're so predictable, aren't they? Same trigger, same delay, often the exact same subject line structure: 'Did you forget something?' Lucas: Exactly. That pattern is exactly what spam filters now look for. And look — I want to be honest for a second. This show stays ad-free, and part of the reason we can dig into really specific tactical stuff like this is that a small group of listeners chips in monthly through buy me a coffee dot com slash fexingo. It's a tiny thing, but it keeps us from having to chase sponsors. So if these deep dives have saved you time or money, that's the way to keep them coming. Luna: Yeah, it's a great model. And it means we can talk about actual problems without glossing over the vendor that caused them. Lucas: Exactly. So let's talk about why abandoned cart emails are getting flagged. It starts with sender reputation — specifically, shared IP reputation in large automation platforms like Klaviyo, Mailchimp, or HubSpot. When thousands of merchants all send 'You left something behind' emails from the same IP range, and a few bad actors on that range trigger spam complaints, the entire pool gets downgraded. Luna: So even a perfectly clean sender gets punished because the neighbor in the IP pool is sending sketchy stuff? Lucas: Yes. But it gets worse. In early 2025, Microsoft rolled out what they call the Smart Filter for transactional email. It's an algorithm that specifically scores emails based on send time consistency, subject line repetition, and the ratio of identical content across senders. Abandoned cart emails tick every box. Luna: What's the ratio they look for? Is there a threshold? Lucas: Microsoft hasn't published the exact number, but testing from deliverability consultancy Email on Acid found that when more than 40% of emails from a shared IP cluster use the same subject line pattern, the cluster's deliverability drops by an average of 22 percentage points. Gmail's similar filter, launched late 2024, penalizes senders whose triggered emails arrive within five minutes of each other from multiple merchants. Luna: So the customer adds something to a cart at 2 PM, and then at 2:15, seven different stores all send 'Did you forget?' — Gmail sees that burst and says, 'this looks like a bulk operation.' Lucas: Correct. And it's not just the subject line. The entire HTML structure of most abandoned cart emails is nearly identical across brands — a hero image, a 'Shop Now' button, a countdown timer. That structural similarity is another signal the filter uses. Luna: So what's the fix? Do you move to a dedicated IP? That's expensive for small merchants. Lucas: Dedicated IP helps, but it's not enough on its own because the filter is also looking at timing patterns. A better first step is randomization. Instead of sending the first abandoned cart email exactly 60 minutes after abandonment, randomize between 45 and 75 minutes. Instead of the same subject line every time, rotate through five variations with different syntax — question, statement, personalization, product mention, urgency. Luna: And does that actually move the needle? I've seen some tests where randomization only improved deliverability by a couple of points. Lucas: It depends on the baseline. For one mid-market apparel brand we worked with, they went from a 12% inbox rate to 34% just by adding a 10-minute random delay and varying the subject line structure. That's a triple improvement. But the bigger lever is something else — sending from a separate subdomain. Use a dedicated sending subdomain for transactional emails, something like 'order.yourbrand.com' instead of 'mail.yourbrand.com'. That isolates your reputation from marketing emails. Luna: That makes sense — it's like a firewall for your sender score. Lucas: Exactly. And it's cheap — it's just a DNS record. The problem is most platforms don't set it up by default. You have to request it. HubSpot and Klaviyo both offer it on their business plans, but you have to ask support to enable it. Luna: How long does it take to see results after you make those changes? Lucas: Usually two to four weeks. Mailbox providers update their reputation scores gradually. But you can accelerate it by warming the new subdomain — start with a low volume of highly engaged recipients, then ramp up over a week. Luna: Is there a tool that monitors whether your abandoned cart emails are landing in spam? Besides manually checking? Lucas: Yes — services like GlockApps or MXToolbox can run deliverability tests from real mailboxes. But the cheapest way is to set up a seed list with Gmail, Outlook, and Yahoo addresses, and check the spam folder for each campaign. Do it once a month. Luna: I think a lot of marketers don't even think to check — they assume transactional email always lands in the inbox. Lucas: That assumption is exactly what's costing them conversions. One final point: the fix isn't just technical. It's also operational. If you're running abandoned cart emails, audit the full sequence at least quarterly. Look at subject line uniqueness, send time distribution, and HTML template diversity. And if you're on a shared IP, consider a private IP once you hit about 100,000 sends per month. Luna: That's a solid threshold. So the takeaway for today: your automation might be killing itself, but the fix doesn't require a new platform. Lucas: Exactly. A few configuration changes — subdomain separation, random delay, subject line variation — and you can reclaim a huge chunk of that lost open rate. It's not glamorous, but it works.