1B Mail or Thunderbird?
A modern alternative to Thunderbird
Thunderbird is a mature, open-source program used by millions. If you'd like something different — real conversations, an inbox that sorts itself, labels in every account and your phone in sync — 1B Mail may suit you better. Here is an honest look at both.
Why people try 1B Mail
Real conversations
Every account in one inbox, and your replies gathered into each conversation, even when they live in Sent.
An inbox that sorts itself
Focused and Other for every account. With 1B Mail Pro, tabs for Updates and Receipts & alerts. Sorting runs on your own device.
Labels in every account
Gmail labels stay real Gmail labels; on IMAP servers, labels are saved as keywords the same way Thunderbird saves tags, so both programs see the same thing.
Computer and phone in sync
Accounts, labels and sidebar move between Windows, Linux and Android, end-to-end encrypted with a phrase only you know. Passwords never leave your devices.
Side by side
Checked in October 2026 against each product's own website. Where Thunderbird does more, we say so.
| 1B Mail | Thunderbird | |
|---|---|---|
| Windows and Linux | Yes | Yes |
| macOS | —No | Yes |
| Android | Yes | Yes |
| iPhone and iPad | —No | In development |
| Open source | —No | Yes (MPL 2.0) |
| Calendar and contacts | —No | Yes |
| POP3 accounts | —No | Yes |
| Add-ons | —No | Yes |
| OpenPGP encryption | —No | Yes |
| Remote images blocked until you allow them | Yes | Yes |
| Focused and Other inbox | Yes | —No |
| Imports accounts, signatures and saved passwords from Thunderbird | Yes | — |
Thunderbird information from thunderbird.net and support.mozilla.org, October 2026. Things change: if something here is out of date, tell us at 1bytesystems@gmail.com.
When Thunderbird is the better choice
- You want calendar, contacts or POP3 in the same program.
- You rely on add-ons or OpenPGP encryption.
- You use a Mac.
- Open-source licensing matters to you: 1B Mail isn't open source.
Moving takes one step
- Step 1
Install 1B Mail
On Windows or Linux, from this website. No administrator rights needed on Windows.
- Step 2
Import from Thunderbird
1B Mail finds your Thunderbird profile and brings over your accounts, identities, signatures and saved passwords.
- Step 3
Keep Thunderbird if you like
Your Thunderbird stays exactly as it is, and labels saved as IMAP keywords show up in both programs.
Questions
Is 1B Mail open source like Thunderbird?
No. 1B Mail is proprietary software by 1Byte Systems. To make it verifiable, we publish every connection it makes, checked in the source code.
Will importing change my Thunderbird?
No. 1B Mail only reads your Thunderbird profile. Thunderbird keeps working as before, and you can use both.
Does my email go through your servers?
No. 1B Mail connects straight to your mail servers. If you turn on sync, our server only receives your account settings and labels, encrypted on your device — never your messages.
Thunderbird is a trademark of the Mozilla Foundation. 1B Mail is not affiliated with or endorsed by Mozilla or MZLA Technologies.
Try it yourself
Download 1B Mail for Windows or Linux, or get it on Google Play for Android.