Proton Mail vs Microsoft 365 Business
On privacy it's Proton Mail. On price it's Proton Mail. On features it's Microsoft 365 Business. Here's everything side by side, last checked 23 October 2026.
Proton Mail or Microsoft 365 Business: which should you choose?
- Proton Mail suits you best if you want end-to-end encryption built in; a company that isn't funded by advertising; and a cheaper plan, at $3.99 a month, yearly ($4.99 monthly).
- Microsoft 365 Business is the better pick if you want more room (50 GB, against 15 GB); to read your mail in any app, such as Apple Mail, Outlook or Thunderbird; and features the other lacks, like POP3 as well as API.
| Feature | Proton Mail | Microsoft 365 Business |
|---|---|---|
| Overall | 4.5 | 2.5 |
| Privacy | 5.0 | 1.0 |
| Price | 4.0 | 2.5 |
| Features | 4.5 | 5.0 |
| Cheapest plan | Mail Plus $3.99 a month, yearly ($4.99 monthly) | Business Basic £5.40 per user a month, yearly, ex VAT |
| Free plan | Yes, 1 GB, no own domain | No |
| Storage | 15 GB | 50 GB |
| Your own domain | ✓ 1 | ✓ Yes |
| End-to-end encryption | ✓ Built in | No |
| Company based in | Switzerland | United States |
| Your data is kept in | Switzerland | UK data centres for UK tenants (London, Cardiff, Durham) |
| Founded | 2014 | 2011 |
| Free trial | Free plan; 30-day refund on paid plans | One month free on some plans |
| Funded by advertising | No | Yes, or its parent company is |
| Works in any mail app | With Proton Bridge on paid plans | ✓ IMAP and SMTP |
| Calendar and contacts | ✓ Yes | ✓ Yes |
| Aliases | 10 addresses | Yes |
| Open-source apps | ✓ Yes | No |
| Sign up without ID | ✓ Yes | No |
| White label | No | No |
| Reader offer | Offer Proton's current deals | None |
| Last checked | 23 October 2026 | 22 October 2026 |
Want to add another? Open this in the compare tool.
The key differences
- On price: Proton Mail Mail Plus at $3.99 a month, yearly ($4.99 monthly), against Microsoft 365 Business Business Basic at £5.40 per user a month, yearly, ex VAT.
- For free, Proton Mail gives you a free plan (1 GB, no own domain), and Microsoft 365 Business no free plan.
- Proton Mail comes with 15 GB of storage and Microsoft 365 Business with 50 GB of storage.
- Proton Mail keeps your mail in Switzerland, while Microsoft 365 Business keeps it in the UK data centres for UK tenants (London, Cardiff, Durham).
- Proton Mail is based in Switzerland and Microsoft 365 Business in the United States, so different privacy laws apply.
- Proton Mail encrypts mail end to end; Microsoft 365 Business doesn't encrypt mail end to end.
- Proton Mail works in other mail apps through Proton Bridge on paid plans, and Microsoft 365 Business works in any mail app over IMAP.
- Only Microsoft 365 Business is part of an advertising business.
- For extra addresses, Proton Mail has 10 addresses and Microsoft 365 Business has yes.
Proton Mail and Microsoft 365 Business: your questions
Which is more private, Proton Mail or Microsoft 365 Business?
Proton Mail scores 5 out of 5 for privacy and Microsoft 365 Business 1. Proton Mail gives you end-to-end encryption built in, a company that isn't funded by advertising and open-source apps.
Which is cheaper, Proton Mail or Microsoft 365 Business?
Proton Mail is cheaper. Its Mail Plus plan is $3.99 a month, yearly ($4.99 monthly), against £5.40 per user a month, yearly, ex VAT for Microsoft 365 Business's Business Basic. Proton Mail also has a free plan. Check the renewal price before you pay, as some first-year prices go up.
Do Proton Mail and Microsoft 365 Business work with my own domain?
Yes, both do. Proton Mail: 1 domain on its cheapest plan that allows one. Microsoft 365 Business: Yes.
Where do Proton Mail and Microsoft 365 Business keep my email?
Proton Mail keeps it in Switzerland. Microsoft 365 Business keeps it in the UK data centres for UK tenants (London, Cardiff, Durham).
Do Proton Mail and Microsoft 365 Business work in other mail apps?
Proton Mail works in other mail apps through Proton Bridge on paid plans. Microsoft 365 Business works in any mail app over IMAP.
Prices and the latest news
- 27 July 2026 Microsoft 365 Business: £5.40 (UK price change from 1 July 2026)
- 1 June 2026 Microsoft 365 Business: £4.90
The latest headlines: Proton Mail news · Microsoft 365 Business news.
Alternatives to Proton Mail and Microsoft 365 Business
Proton Mail vs mailbox.org · Microsoft 365 Business vs mailbox.org · Proton Mail vs Posteo · Microsoft 365 Business vs Posteo · Proton Mail vs Tuta · Microsoft 365 Business vs Tuta
Switching between them
Switching takes an evening to set up. Follow the steps for your direction: Proton Mail to Microsoft 365 Business · Microsoft 365 Business to Proton Mail.