Why we rebuilt Mailbird from scratch: a note from our founder
Mailbird's co-founder on why we rebuilt Mailbird from the ground up, what we kept from 2012, and what we believe email should feel like in 2026.
This week we launched Mailbird Next. Before you read about the features, I want to tell you why it exists at all, because rebuilding an email app that millions of people already use is not a small decision.
For me, the issue wasn't that people had stopped loving Mailbird. It was the gap between what we wanted to build for them and how quickly we could deliver it. We wanted a faster, more stable product that could improve rapidly across all platforms, not different versions moving at different speeds. The email client people would rely on for the next decade needed a different, modern foundation.
Where it started
Mailbird began in 2012 on Bali, at an entrepreneurial retreat called Project Getaway. Michael Olsen and I were surrounded by founders, and we kept hearing the same complaint: email, especially on Windows, was painful.
We came up with the name and started building. We launched on April 2, 2012, and TechCrunch called us "the Sparrow for Windows", after the much-loved Mac email client Google had just bought. Andrea Loubier joined us and became Mailbird's first CEO.
The idea was simple then and it still is: every email account in one calm, unified inbox.
One early detail has stayed with me. In April 2013, Andrea shared an email from a user who said he was surprised not just by how quickly we replied, but that the reply was human and actually addressed his problem. I forwarded it internally, saying that this kind of support should be a core part of our company.
That captures something important about those early days: we weren't only building software. We were building a relationship with the people using it, and we cared deeply about their needs and their wishes for a better Mailbird.
Why the old Mailbird had to change
Over the next decade Mailbird became one of the best-known email clients on Windows, and more than 3 million people registered for it. But it was built for Windows alone, on foundations laid in 2012.
The original foundations were built for our Windows product. Next needed to support a much broader future: one product across Windows, Mac, mobile/tablets, and later, Linux.
Keeping separate codebases moving means duplicated effort, differences between platforms, and more work just to keep them aligned. The rebuild wasn't about throwing away everything we'd learned. It was about putting those lessons into a foundation that would let us move much faster.
Users shouldn't need to care about our codebase. They should feel the benefit in the product, and in the far faster speed at which we can deliver new features and value to our customers.
"Mailbird Next is about making sure we could keep delivering a delightful daily email experience for our users. Recently a customer shared a great idea for a minimal layout design upgrade, and we were able to build and launch it just 3 days after receiving the feedback."
Starting over, one platform at a time
In 2020 we started rebuilding Mailbird from the ground up, on one codebase for every platform. We shipped the first product from it, Mailbird for Mac, in October 2024. It reached the Mac App Store worldwide in September 2025.
The important thing about Mac-first was focus. Windows users already had an established product. We needed to make the new Mac experience genuinely great, with a real Mac feel, before widening our attention again.
The Mac launch also reinforced that design alone isn't enough. People need the everyday workflows and platform-specific details they rely on. In 2025, I reached out to a reviewer who'd been disappointed by Mailbird for Mac, thanked him for the feedback, and asked what we should improve. We'd already added things he'd highlighted, including Rules & Filters and Send Later. That's the approach I want us to keep: listen and improve.
What we kept, and what we changed
We kept the idea people signed up for: every account in one place, set up in minutes, with the apps you use every day in a panel beside your mail.
We changed almost everything underneath it:
- One app for Windows, Mac, Android, and iPhone. The same app and the same account setup on both.
- Private by design. Your mail is still stored on your device, never on our servers, and now designed around our on-device Privacy Hub which blocks trackers, spam, untrusted senders, and images.
- Getting Things Done, on desktop and mobile. Sort your inbox on your phone, sending each email to To Do, To Read, snooze, or archive, and the same lists are waiting when you open Mailbird on your desktop later.
- AI on your terms. You can connect the AI app you already use. It stays off until you turn it on, and we never train on your email.
- Faster releases. Mailbird Next has shipped a release most weeks this year.
The biggest thing for me is bringing Windows and Mac onto the same modern foundation: it changes how quickly we can improve the whole product, including now adding Mobile to the Mailbird product family. A better Mailbird today is important; being able to keep making it better is even more important in the world we live in now.
On the everyday side, I'd highlight the built-in calendar and the work on speed, stability, and the interface. These are things you feel while getting through a normal working day, not just while watching a demo.
I'm also excited about where we're taking optional, on-device AI. But I'd keep that clearly separate from what's available today. People who don't want AI should still get an excellent email client.
What we believe email should be
Our goal hasn't changed since Bali: a healthy relationship with email, for individuals and for the businesses that run on it. Email should be intuitive, fast, private, and enjoyable to use every day, with AI there to make it more convenient when you want it.
Launch is a starting point. The Android app is available now in beta, ready for you to test-drive, and the iOS app will be available soon. Wingman, our own on-device assistant, is in beta testing and will be launching soon.
To everyone who has used Mailbird for years: thank you for sticking with us, challenging us, and telling us where we need to do better. Next is an investment in the future of the product you chose. Our job is to keep earning your trust, with what we build and how we treat you.
And if you're trying Mailbird for the first time: you don't need to know anything about our rebuild. Try it with the accounts you already use, and tell us whether it makes your day easier. That's the test that matters.
Michael Bodekaer Jensen, CEO and co-founder
