MZLA Technologies (Mozilla)
Thunderbird
Free, open-source desktop email client funded by donations, now also on Android.
Price, checked Oct 26, 2026FreeTry Thunderbird free
Thunderbird vs Microsoft Outlook
Pricing, platforms and features side by side, where the two differ, and who each one suits.
Thunderbird pricing and alternatives
Microsoft
Microsoft Outlook
Microsoft's email and calendar app; free with ads, ad-free with a Microsoft 365 plan.
Price, checked Oct 26, 2026Free plan · paid from $1.67/user/moTry Microsoft Outlook free
Side by side
| Feature | Thunderbird | Microsoft Outlook |
|---|---|---|
| Price | Free | Free plan · paid from $1.67/user/mo |
| Works on | Mac, Windows, Linux, Android | Mac, Windows, iPhone, Android, Web |
| Accounts | Gmail, Outlook, Any IMAP | Gmail, Outlook, iCloud, Any IMAP |
| AI features | – | Yes |
| Shared inbox | – | Yes |
Rows where the two differ come first. Prices from each vendor's pricing page.
Where only one fits
- Microsoft OutlookiCloud
- device
- Microsoft OutlookiPhone
- must-haves
- Microsoft OutlookAI replies and summariesShared team inbox
Ranked in our guides
| Guide | Thunderbird | Microsoft Outlook |
|---|---|---|
| Best email apps for Gmail | #8 | #3 |
| Best email apps for Outlook | #3 | #2 |
| Best email apps for Mac | #8 | #1 |
| Best AI email apps | – | #5 |
We don't test apps ourselves. Features and prices come from each vendor's own site; guide ranks follow what independent reviewers recommend.