Stay with Apple Mail if you work on a Mac and like a built-in app that files messages into categories for you and offers Apple's writing help. Choose Thunderbird if you'd rather have a free, open-source client that also runs on Windows and Linux, can merge your accounts into one inbox and is kept going by donations instead of ads.
Apple Mail comes with the Mac, and Thunderbird is usually the next name you hear. Most people searching this have a reason: the built-in app feels limiting, they've added a Windows or Linux machine to their week, or they'd simply like their email in software that isn't tied to one company's hardware. Both apps gather several accounts into one window, so the real differences sit elsewhere, and that's what this page walks through.
The writing help that depends on where you live
According to Apple's guide, Mail can boil a highlighted passage down to its key points, look over a draft for slips and suggest new phrasing, through a set of features called Writing Tools that run on Apple Intelligence. The same guide adds a line that's easy to skim past: Apple Intelligence isn't offered in every language or region on the current macOS. So before you stay put because of the drafting help, make sure it's switched on where you are and in the language you write in.
Thunderbird's own page makes a very different kind of promise: it does not secretly train AI with your private conversations. That's a statement about what it won't do with your mail, not a writing feature, so the two apps aren't offering the same thing at all. One is selling help with your words; the other is promising to keep its hands off them.
Which of those matters more is a personal call. If drafting help is the draw, Apple's route is the obvious one, as long as it's live for you. If keeping your inbox out of AI training is the priority, read each company's privacy terms in full before you decide.
The two apps side by side
| Apple Mail | Thunderbird | |
|---|---|---|
| Type | Built into the Mac | Free, open-source desktop app |
| Runs on | Mac | Windows, Linux, macOS |
| Phone app | Not listed | Android |
| Accounts | All in one app | Unified or separate |
| Auto sorting | Categories | Not listed |
| Blocking | People or groups | Not listed |
| AI | Writing Tools, not in every region | No secret training on private mail |
| Calendar and contacts | Not listed | Built in |
| Funding | Not listed | Donations, no inbox ads |
| Licence | Not listed | MPL 2.0 |
If a row you rely on reads 'Not listed', look it up in that app's own help pages before you plan around it.
Who's better off staying with Apple Mail
- You work on a Mac and you'd rather not install anything new.
- You like the idea of mail being sorted into categories for you, without building filters by hand.
- You want a quick way to stop particular senders, or whole groups of them, from reaching you.
- You draft a lot of messages and the writing help is live for your language and region.
The appeal here is that there's nothing to set up and nothing to learn. If what you want from email is a tidy inbox that comes with the computer, the built-in app is a sensible place to stay. If you're also weighing Microsoft's client, there's a separate look at Apple Mail against Outlook that covers that pairing.
Who's better off making the switch
- Your week is split between a MacBook and a Windows or Linux machine, and you'd like one familiar program on both.
- Your diary and address book should sit in the same desktop program as your messages.
- Several addresses come in every day and you'd like them merged, with the option to split them again.
- Being able to read the source and see the published licence is important to you.
- Software paid for by its users, with nothing advertised between your messages, sits better with you.
- You carry an Android phone and like having a mobile app from the same project.
This is the stronger choice for mixed households and mixed offices, where one person might be on a MacBook while another is on a Windows laptop. Having one app everywhere means one set of habits, one place to look for settings and fewer 'where's that button on yours?' conversations.
How each one is kept going
Apple Mail ships with the Mac, so there's nothing extra to install. Thunderbird's code sits under the MPL 2.0 licence, and the project says users' donations pay the bills instead of ads placed in your inbox.
That difference shapes what each one asks of you. With the built-in app you're relying on Apple's choices about features and regions. With Thunderbird, you're relying on an open-source project whose code anyone can read, and which asks its users to chip in if they can. Neither is better in the abstract; it depends which of those you're more comfortable with.
Where they overlap
Strip away the branding and both apps do the core job: they pull mail from more than one account into a single place, so you're not logging into several webmail tabs every morning. Apple's guide talks about managing all your accounts from one app, and Thunderbird offers the same, with a choice of a combined inbox or separate ones.
Want AI doing the heavy lifting in your marketing?
I build the systems that handle the boring 80 percent, so you get your week back. Done properly, with the human kept in.
Both are also programs you run on your computer rather than websites, so either can sit alongside whatever webmail your provider gives you. You don't have to give up the browser version to use a desktop client. Plenty of people keep both, using the app at their desk and the web inbox when they're on someone else's machine.
If you're rethinking the email service itself rather than just the app you read it in, that's a separate decision. A roundup of other hosted email services is a better starting point for that one.
A one-week trial before you commit
- Add one email account to the new app and leave your current app running alongside it, so nothing is at risk while you compare.
- After the first sync, open your busiest folders in both apps and check that the same messages appear in each.
- If you're relying on the writing help, confirm it appears for your language and region before you plan around it.
- If calendar and contacts are part of the reason you're moving, add them only once mail is working smoothly.
- Try the combined view and the per-account view for a couple of days each, and keep whichever suits how you work.
- Set up any blocked senders or sorting you depend on, then watch for a few days to see what slips through.
- Remove the account from the old app only after a full week has gone by with nothing missing.
A week sounds slow, but it catches the things a quick test misses: the newsletter that only arrives on Fridays, the shared folder you open once a month, or the client who replies from an address you'd forgotten about.
Frequently asked questions
Does Apple Mail work on a Windows computer?
Apple's guide is written for the Mac, so plan on a different program for a Windows PC.
Do I lose my mail if I stop using Apple Mail?
Check with your email provider where your messages are stored before you remove an account from any app, and keep a backup until you're sure.
Where's Apple's official help for Mail?
Apple publishes a Mail user guide for the Mac, which is the place to check setup steps and any feature you're unsure about.
Can I switch off Mail's automatic categories?
Apple's Mail guide is the place to check how categories are set up and changed on your version of macOS.
Is there an iPhone version?
Not one Thunderbird mentions: its mobile app is for Android. Check its own site before you plan around one.
Can I bring my existing messages across from Mail?
Import steps live in the new app's support section. Leave the old app untouched until every folder has arrived.
