Email has outlasted every channel that was supposed to replace it. Social media, push notifications, in-app messaging – all of them arrived with predictions that inbox marketing was finished. None of them came close.
According to Litmus’s 2025 State of Email report, marketers see returns between 36 and 42 dollars for every dollar spent on email. The DMA puts the UK average at $38 to $1. In U.S. ecommerce, Omnisend has measured returns as high as $72 per dollar. No other digital channel comes near those numbers, and the gap has held up year after year.
But those figures carry a hidden assumption. They assume the email arrived.
Why email still leads – and why it’s easy to take for granted
The reason email keeps outperforming other channels is straightforward. It’s direct, it’s personal, and it’s owned. No algorithm decides how many of your subscribers see your message. No platform changes its rules and cuts your reach overnight. You send to people who choose to hear from you, through a channel they check multiple times a day.
That dynamic explains why 41 percent of marketers told Litmus it was their most effective channel – ahead of paid search, SEO, and social media. It’s also why it’s so easy to stop thinking critically about how it works. Email has always worked. Until it doesn’t.
The number nobody puts in the ROI calculation
Here’s what the benchmark reports don’t advertise. The average inbox placement rate across all senders sits at around 83 percent, according to Validity’s 2025 data. For software companies specifically, it drops to about 81 percent. That means roughly one in five emails from a typical SaaS product never reaches the person it was sent to.
On a 100,000-email campaign, that’s 19,000 messages that were paid for, written, tested, and scheduled – and then quietly filtered into spam or swallowed entirely. The revenue tied to those sends disappears without a trace. It doesn’t show up as a failed delivery. It just doesn’t show up at all.
The compounding effect is what makes it expensive. Research on high-volume programs found that moving inbox placement from 85 percent to 97 percent on a $10 million email-driven program recovers roughly $1.4 million in annual revenue. The ROI figures that make email famous are the ceiling. Deliverability determines how close any program actually gets to its goal.
Two problems that grow quietly until they don’t
Most deliverability failures trace back to the same two infrastructure decisions – both of which tend to be made early, never revisited, and invisible until something breaks.
The first is stream mixing. A lot of companies, especially ones that scaled quickly, send everything through the same setup. Marketing campaigns, password resets, billing alerts, welcome messages – one domain, one IP address, one sender reputation. Mailbox providers don’t separate them. They see one sender, and they score everything that sender does. When a promotional campaign generates spam complaints or low engagement, that score drops for every email the domain sends, including the ones users are genuinely waiting for.
The second is authentication. SPF, DKIM, and DMARC are the protocols that tell mailbox providers an email is genuinely coming from the domain it claims to represent. Google and Yahoo made them mandatory for bulk senders in February 2024, with Microsoft following with its own enforcement in 2025. Yet according to Sinch Mailjet’s Road to Inbox 2025 report, only about 54 percent of senders had DMARC in place as of last year. More than a quarter weren’t sure whether their domains were properly authenticated at all.
That last detail matters. Without authentication, even a clean list and well-crafted content can end up in spam. The mailbox provider can’t verify who sent it, so it errs on the side of caution.
This isn’t a content problem
The instinct when open rates drop is to fix the copy. Rewrite the subject line. Clean the list. Improve segmentation. Those things help at the margins, but they can’t compensate for structural problems underneath them.
Shared IP addresses are one of the most common structural problems for growing companies. When a business scales past its original email setup, it often stays on shared infrastructure out of inertia. That means its sender reputation is partly determined by everyone else on the same server. One bad actor on a shared IP can drag down inbox placement for every account it serves.
Dedicated IPs solve that problem but introduce another one. A new dedicated IP has no history. Mailbox providers treat it with suspicion until it earns a reputation through a gradual warmup – a process that takes weeks of carefully managed volume increases. Skip it, and the dedicated IP gets flagged before it becomes useful.
And then there’s the visibility gap. What lands in Gmail’s primary tab might be hitting Outlook’s junk folder at the same time. Without per-provider monitoring, that kind of split can persist for weeks before anyone connects the drop in engagement to its actual cause.
A market catching up to the problem
The email infrastructure market reached $1.2 billion in 2024 and is projected to grow to $1.9 billion by 2030, according to ResearchAndMarkets. That growth reflects something real: companies are starting to treat deliverability as infrastructure, not a background setting.
Mailtrap, built by Ukrainian software studio Railsware, has taken a distinct approach for the segment where marketing and transactional email intersect. The company’s origin is telling. ‘When you do something for yourself, it works good for you and then it might work well for your community as well,’ Sergiy Korolov, co-CEO of Railsware, said in a 2025 interview with SaaS Club. Mailtrap started as exactly that – an internal fix for a real problem, before becoming a platform used by over 150,000 customers.
The platform separates transactional and bulk sends at the infrastructure level, so a marketing campaign can’t damage the sender reputation that password resets and billing alerts depend on. Analytics break down performance by mailbox provider, so teams can tell the difference between a Gmail problem and an Outlook problem rather than chasing aggregate numbers. For companies that own both marketing and product email flows, that kind of visibility is hard to find in one place.
Other providers have carved out distinct positions as a result. Amazon SES is the lowest-cost option at $0.10 per thousand emails, built for teams with the technical capacity to manage their own configuration. Twilio SendGrid handles enterprise volume and offers a wide integration ecosystem. Postmark has a strong reputation among developers who need fast, reliable delivery for transactional messages. Mailgun serves a broad developer audience with flexible API tooling.
The ROI is real. But it isn’t guaranteed.
Email marketing’s returns are well-documented and consistently outperform every comparable channel. They are also not automatic.
The teams that actually realize those returns tend to share a few habits. They authenticate their domains before they launch. They separate transactional and marketing infrastructure from the start. They watch inbox placement by provider, not just the number their sending platform reports as delivered.
Email works. The question is whether the infrastructure underneath it is letting it.
