Microsoft 365 Business vs Firefox Relay
They tie on privacy, Firefox Relay wins on price and Microsoft 365 Business wins on features. Every fact below was checked on or before 25 October 2026.
Which should you choose?
- Microsoft 365 Business is the better pick if you want your email to stay in the UK data centres for UK tenants (London, Cardiff, Durham); email at your own domain name; and more space for your mail: 50 GB.
- Firefox Relay is the better pick if you want a company that isn't funded by advertising; a cheaper plan, at $0.99 a month; and a free plan before you pay anything.
| Feature | Microsoft 365 Business | Firefox Relay |
|---|---|---|
| Overall | 2.5 | 2.5 |
| Privacy | 1.0 | 1.0 |
| Price | 2.5 | 5.0 |
| Features | 5.0 | Not rated |
| Cheapest plan | Business Basic £5.40 per user a month, yearly, ex VAT | Premium $0.99 a month |
| Free plan | No | Yes, 5 aliases |
| Storage | 50 GB | Forwards only |
| Your own domain | ✓ Yes | Own subdomain only |
| End-to-end encryption | No | No |
| Company based in | United States | United States (Mozilla) |
| Your data is kept in | UK data centres for UK tenants (London, Cardiff, Durham) | United States |
| Founded | 2011 | 2020 |
| Free trial | One month free on some plans | Free plan |
| Funded by advertising | Yes, or its parent company is | No |
| Works in any mail app | ✓ IMAP and SMTP | No, its own apps only |
| Calendar and contacts | ✓ Yes | No |
| Aliases | Yes | Unlimited aliases |
| Open-source apps | No | ✓ Yes |
| Sign up without ID | No | No |
| White label | No | No |
| Reader offer | None | None |
| Last checked | 22 October 2026 | 25 October 2026 |
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The key differences
- Microsoft 365 Business's cheapest plan is Business Basic (£5.40 per user a month, yearly, ex VAT); Firefox Relay's is Premium ($0.99 a month).
- For free, Microsoft 365 Business gives you no free plan, and Firefox Relay a free plan (5 aliases).
- Microsoft 365 Business comes with 50 GB of storage and Firefox Relay with no storage, as it forwards mail on.
- Data location: UK data centres for UK tenants (London, Cardiff, Durham) for Microsoft 365 Business, United States for Firefox Relay.
- Microsoft 365 Business is based in the United States and Firefox Relay in the United States (Mozilla), so different privacy laws apply.
- Microsoft 365 Business lets you bring your own domain name; Firefox Relay doesn't.
- Microsoft 365 Business works in any mail app over IMAP, and Firefox Relay only works in its own apps.
- Only Microsoft 365 Business is part of an advertising business.
- For extra addresses, Microsoft 365 Business has yes and Firefox Relay has unlimited aliases.
Common questions
Which is more private, Microsoft 365 Business or Firefox Relay?
They score the same for privacy: 1 out of 5 each. The differences are in the details, such as where your mail is kept (the UK data centres for UK tenants (London, Cardiff, Durham) for Microsoft 365 Business, the United States for Firefox Relay).
Which is cheaper, Microsoft 365 Business or Firefox Relay?
Firefox Relay is cheaper. Its Premium plan is $0.99 a month, against £5.40 per user a month, yearly, ex VAT for Microsoft 365 Business's Business Basic. Firefox Relay also has a free plan. Check the renewal price before you pay, as some first-year prices go up.
Do Microsoft 365 Business and Firefox Relay work with my own domain?
Only Microsoft 365 Business does (Yes). With Firefox Relay your address stays on its own domain.
Where do Microsoft 365 Business and Firefox Relay keep my email?
Microsoft 365 Business keeps it in the UK data centres for UK tenants (London, Cardiff, Durham). Firefox Relay keeps it in the United States.
Do Microsoft 365 Business and Firefox Relay work in other mail apps?
Microsoft 365 Business works in any mail app over IMAP. Firefox Relay only works in its own apps.
Price changes and 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 · Firefox Relay news.
Not sold on either? Try these
Microsoft 365 Business vs mailbox.org · Firefox Relay vs mailbox.org · Microsoft 365 Business vs Posteo · Firefox Relay vs Posteo · Microsoft 365 Business vs Proton Mail · Firefox Relay vs Proton Mail
Moving your email
Moving to Microsoft 365 Business · Moving from Microsoft 365 Business. Or see all my switching guides.