I used Outlook as my default client for the longest time, but then I switched to Thunderbird, a free and open-source email client from Mozilla. However, it has a critical flaw, the lack of a native conversation view, which is an essential feature for me in any email client. I could add this functionality with a plugin, but a plugin is a plugin, and plugins break. That’s exactly what happened after an update. Thunderbird is also resource-hungry, and it can quietly kill your laptop battery without any hint.
So, I went looking for an alternative. After trying a few options, including Blue Mail, Spark Mail, and eM Client, I settled on Mailspring. It’s a cross-platform, ad-free app that, despite a few quirks, works for my needs and is overall a better client than both Outlook and Thunderbird.
Modern UI and clean layout
A polished interface that doesn’t feel like a typical open-source app
Mailspring is an open-source app that is free to use and, more importantly, completely ad-free, if you excuse the rare upgrade dialog, but more on that later. The first thing I noticed when I opened it was how modern it looks. A lot of open-source email clients feel like they were designed a decade ago and never updated. Mailspring doesn’t have that problem.
The layout follows the classic three-pane design you’d expect from a proper desktop client. Your folders sit on the left, the message list runs down the middle, and the opened email takes up the right side. Nothing feels cramped, and everything has room to breathe. When you reply to an email, a rich-text editor opens inline in the same pane, so you can format your message and send it without jumping to a separate window.
There’s also a contact sidebar that shows information about the sender along with your past conversations with them. It’s a small touch, but it gives you context without cluttering the screen.
The feature that made me stay, though, is the conversation view. Mailspring groups related messages into a single thread, so a back-and-forth exchange reads like a chat instead of a pile of separate emails. This is the one thing Thunderbird couldn’t do natively, and Mailspring handles it well right out of the box.
Covers all the essentials well
Every standard email feature is here, plus a few extras
A modern look only goes so far if the basics aren’t covered, and this is where Mailspring quietly earns its place. It handles everything you’d expect from a serious desktop client without making you hunt for it.
You can add multiple accounts and manage them in one place, with full support for folders and labels. Mailspring works as a normal IMAP and SMTP client, so composing, replying, and forwarding all behave the way you’re used to. You also get mail rules to auto-process incoming messages, scheduled sending to deliver the mail later, and per-address signatures so your work and personal accounts can look different.
What’s more, Mailspring has a proper signature designer where you can edit the raw HTML, which makes building polished signatures with logos and links far easier than a plain text box. It also includes read receipts and link tracking, so you can tell whether a message was opened or simply ignored.
One lesser-known touch I appreciate is the built-in translation. Mailspring can translate the body of an email inside the app and toggle back to the original, which is handy when you get messages in a language you don’t read.
Plenty of customization and automation
Tweak the look, the shortcuts, and how your mail is handled
If the essentials cover what you need, the customization options let you shape Mailspring around how you actually work. There’s a surprising amount of depth here for a free app.
Under Preferences > Appearance, you can switch between a single-panel or two-panel layout depending on how much you want to see at once. Mailspring also ships with several built-in themes, including Light, Dark, Dark Side, and Ubuntu, and you can import custom themes to match your desktop. The Keyboard Shortcuts section is just as flexible. You can pick a scheme that mirrors Gmail, Apple Mail, Inbox, or Outlook, so any muscle memory you’ve built up still works here.
The automation side is where Mailspring saves real time. The Mail Rules tab lets you create rules that trigger on certain conditions and then act on messages automatically, so repetitive triage handles itself. The Templates section lets you save pre-written messages for replies you send often, which is useful for support or recurring responses.
My favorite automation feature is the follow-up reminder. On any sent email, you can ask Mailspring to remind you if no one replies within a set number of days. It quietly resurfaces the thread in your inbox, so a conversation never goes cold just because you forgot about it. Combined with the snooze button, it turns your inbox into a basic task manager.
It’s not without faults
Some performance lag and an optional paid plan
Mailspring has its quirks, and the most annoying one happened right after I installed the app. I kept running into an authentication error every time I tried to add my Google and Outlook accounts. The fix was to skip the standard sign-in and configure each account manually using its IMAP and SMTP details instead. For my Google account, I also had to create a dedicated app password at Google App Passwords, name it something like “Mailspring,” and paste the generated password into the manual setup screen along with my email address. It’s a one-time annoyance, but it doesn’t leave a very good impression if you have to troubleshoot just to get started.
The other issue I’ve run into is performance. The app can feel sluggish at times, and switching between large folders is occasionally slower than it was on Thunderbird. It’s not bad enough to be a deal-breaker, but it’s noticeable, and worth knowing before you switch.
Then there’s the money question. Mailspring has an optional paid plan called Mailspring Pro that costs around $8 per month. It removes the limits on features like snooze, send later, follow-up reminders, and read receipts, and adds more advanced tracking and mailbox insights. I’ve stuck with the free plan because it already covers everything I need from my mail account, and the free version is genuinely usable rather than a crippled trial.
The only reminder that Pro exists is a rare upgrade pop-up. Mailspring showed it to me once, I dismissed it, and it hasn’t bothered me since. There are no grayed-out menus or constant nags pressuring you to pay. As I said earlier, it’s an occasional dialog, not a deal-breaker, and the standard client stays free to use as it is.
- OS
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Windows, Linux, macOS
- Developer
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Foundry 376
Mailspring is a fast, open-source email client for Windows, Mac, and Linux. It supports multiple accounts, unified inbox, read receipts, link tracking, spell and grammar checking, and custom themes — free to use.
A better fit than either client I left behind
After bouncing between Outlook and Thunderbird, Mailspring is the first email client that hasn’t given me a reason to go looking again. It does have trade-offs. It can feel slow at times, and the Pro upsell, however quiet, is still there, because the developers have to make a living.
But for me, the wins outweigh the quirks. I get the native conversation view that Thunderbird never had, a modern interface, and the essentials all working without ads or constant nagging. If you’re tired of Outlook’s clutter or Thunderbird’s plugin headaches, and you mostly want a clean client that just handles your mail well, Mailspring is worth a serious look.