Microsoft 365 Business vs Proton Mail for Business
In short: Proton Mail for Business wins on privacy, they tie on price, and Microsoft 365 Business wins on features. The full comparison is below, last checked 22 October 2026.
Should you pick Microsoft 365 Business or Proton Mail for Business?
- Choose Microsoft 365 Business if you want 50 GB of storage and the choice of any mail app over IMAP.
- Proton Mail for Business suits you best if you want mail that's encrypted end to end without any setup; a provider with no advertising business behind it; and a cheaper plan, at $6.99 per user a month.
| Feature | Microsoft 365 Business | Proton Mail for Business |
|---|---|---|
| Overall | 2.5 | 4.0 |
| Privacy | 1.0 | 4.5 |
| Price | 2.5 | 2.5 |
| Features | 5.0 | 4.5 |
| Cheapest plan | Business Basic £5.40 per user a month, yearly, ex VAT | Mail Essentials $6.99 per user a month |
| Free plan | No | No |
| Storage | 50 GB | 15 GB |
| Your own domain | ✓ Yes | ✓ 3 |
| End-to-end encryption | No | ✓ Built in |
| Company based in | United States | Switzerland |
| Your data is kept in | UK data centres for UK tenants (London, Cardiff, Durham) | Switzerland |
| Founded | 2011 | 2014 |
| Free trial | One month free on some plans | 30-day refund |
| Funded by advertising | Yes, or its parent company is | No |
| Works in any mail app | ✓ IMAP and SMTP | With Proton Bridge on paid plans |
| Calendar and contacts | ✓ Yes | ✓ Yes |
| Aliases | Yes | Yes |
| Open-source apps | No | ✓ Yes |
| Sign up without ID | No | No |
| White label | No | No |
| Reader offer | None | None |
| Last checked | 22 October 2026 | 22 October 2026 |
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The key differences
- On price: Microsoft 365 Business Business Basic at £5.40 per user a month, yearly, ex VAT, against Proton Mail for Business Mail Essentials at $6.99 per user a month.
- Space: Microsoft 365 Business gives 50 GB of storage, Proton Mail for Business 15 GB of storage.
- Microsoft 365 Business keeps your mail in the UK data centres for UK tenants (London, Cardiff, Durham), while Proton Mail for Business keeps it in Switzerland.
- The companies sit under different laws: Microsoft 365 Business in United States, Proton Mail for Business in Switzerland.
- On encryption, Microsoft 365 Business doesn't encrypt mail end to end, whereas Proton Mail for Business encrypts mail end to end.
- Mail apps: Microsoft 365 Business works in any mail app over IMAP; Proton Mail for Business works in other mail apps through Proton Bridge on paid plans.
- Microsoft 365 Business (or its parent company) makes money from advertising; Proton Mail for Business doesn't.
Questions people ask
Is Microsoft 365 Business more private than Proton Mail for Business?
Proton Mail for Business scores 4.5 out of 5 for privacy and Microsoft 365 Business 1. Proton Mail for Business gives you mail that's encrypted end to end without any setup, a provider with no advertising business behind it and apps whose code is public.
Is Microsoft 365 Business cheaper than Proton Mail for Business?
Proton Mail for Business is cheaper. Its Mail Essentials plan is $6.99 per user a month, against £5.40 per user a month, yearly, ex VAT for Microsoft 365 Business's Business Basic. Check the renewal price before you pay, as some first-year prices go up.
Can I use my own domain with Microsoft 365 Business or Proton Mail for Business?
Yes, both do. Microsoft 365 Business: Yes. Proton Mail for Business: 3 domains on its cheapest plan that allows one.
Where is my email stored with Microsoft 365 Business and Proton Mail for Business?
Microsoft 365 Business keeps it in the UK data centres for UK tenants (London, Cardiff, Durham). Proton Mail for Business keeps it in Switzerland.
Can I use Microsoft 365 Business and Proton Mail for Business in Apple Mail or Outlook?
Microsoft 365 Business works in any mail app over IMAP. Proton Mail for Business works in other mail apps through Proton Bridge on paid plans.
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: Microsoft 365 Business news · Proton Mail for Business news.
Not sold on either? Try these
Microsoft 365 Business vs mailbox.org · Proton Mail for Business vs mailbox.org · Microsoft 365 Business vs Posteo · Proton Mail for Business vs Posteo · Microsoft 365 Business vs Proton Mail · Proton Mail for Business vs Proton Mail
Switching between them
Moving to Microsoft 365 Business · Moving from Microsoft 365 Business. Or see all my switching guides.