As of 6 Nov 2026, the panel rates Microsoft 365 Business 3/5 and Proton for Business 3.5/5 in Business Email & Office Suites. Weighted by what each judge cares about, 4 of the 6 judges pick Microsoft 365 Business and 2 pick Proton for Business. Microsoft 365 Business scores higher on 3 of 7 criteria (Calendar, contacts & office apps, Migration, open standards & exit and Mail, domains & deliverability). Proton for Business scores higher on 4 of 7 criteria (European sovereignty, Pricing transparency, Administration, identity & partner management, plus 1 more). Provenance — Microsoft 365 Business: Rest of world; Proton for Business: UK / wider Europe. Ratings are the AI panel’s opinion, formed from public evidence: how scores are made.
Microsoft 365 Business and Proton for Business split this bench. Microsoft 365 Business holds the productivity side: mail and deliverability at 7.0 vs 5.8 and calendar and office at 7.5 vs 6.2, six judges leaning its way on each, plus migration and portability at 7.0 vs 5.7, five judges to one. Proton for Business holds the governance side: security and compliance at 7.3 vs 6.5, where four judges lean Proton and two tie; administration and identity at 7.2 vs 6.3, five lean Proton and one tie; and sovereignty at 6.7 vs 4.5 plus pricing transparency at 7.0 vs 5.8, six judges leaning Proton on each. The weighted totals carry the split through: of five judges with totals shown, the IT administrator, IT service provider and skeptic put Microsoft 365 Business ahead, while the public-sector IT lead and data protection officer put Proton for Business ahead.
Choose Microsoft 365 Business if
You need the office suite itself — documents, spreadsheets and calendars — as the core of the purchase; calendar and office leans Microsoft 365 Business 7.5 to 6.2, six judges to zero.
Your mail operations depend on per-plan limits, quarantine and a hosted Exchange Online setup; mail and deliverability leans Microsoft 365 Business 7.0 to 5.8, six judges to zero.
Your team is moving mail into or out of the platform and wants a documented path both ways; migration and portability leans Microsoft 365 Business 7.0 to 5.7, five judges to one.
You buy the way the IT administrator, the IT service provider or the skeptic does; their weighted totals put Microsoft 365 Business ahead at 6.4 vs 6.3, 6.6 vs 6.4 and 6.5 vs 6.2.
Choose Proton for Business if
You need encryption the provider states it cannot decrypt, backed by ISO 27001 and SOC 2 Type II; security and compliance leans Proton for Business 7.3 to 6.5, four judges lean Proton and two tie.
Your team runs SAML sign-on with Okta or Microsoft Entra ID, three admin roles with a permission matrix, and a SCIM 2.0 API; administration and identity leans Proton for Business 7.2 to 6.3, five judges lean Proton and one tie.
Data sovereignty is your deciding criterion; it leans Proton for Business 6.7 to 4.5, six judges to zero.
You want the steadiest published pricing picture; pricing transparency leans Proton for Business 7.0 to 5.8, six judges to zero.
You buy the way the public-sector IT lead or the data protection officer does; their weighted totals put Proton for Business ahead at 5.9 vs 6.7 and 6.3 vs 7.1.
Read this comparison as one judge. Each weighs the same scores by what they care about.
The IT Service Provider
Runs a six-person IT service company in Austria that looks after mail for forty client firms, from a two-person architect's office to a hotel group. Spends Mondays on mails that landed in spam and phones that stopped syncing. Wants one partner console for every client, DKIM and DMARC set up without a ticket, migrations it can run itself, support that answers within the hour, and margins it can calculate before it quotes.
Microsoft 365 Business
This judge's pick
Proton for Business
Criterion by criterion
Mail, domains & deliverability
Microsoft 365 Business
The Exchange Online service description and limits pages show a platform I could run clients on: ActiveSync with device policies and limits, native Outlook on desktop, web and mobile, a quarantine the admin manages, inbox and transport rules with hard numbers, shared mailboxes up to 100 GB, multi-engine anti-malware and custom outbound routing. But we found no public information on custom-domain DNS set-up, DKIM, DMARC, SPF or MTA-STS, nor on the outbound delivery reputation — the parts I touch every Monday — so I stop short of the top band.
Proton for Business
Custom domains are well documented with SPF, DKIM auto-rotation, DMARC and registrar-specific guides, plus catch-all, groups, spam filtering, automated replies and IMAP/SMTP through the open-source Bridge. We found no public information on Exchange ActiveSync or native Outlook MAPI, DMARC reporting, MTA-STS or DANE, an admin-reviewable quarantine, or send and attachment limits.
Calendar, contacts & office apps
Microsoft 365 Business
Calendar, contacts and tasks ship with the hosted service, with conference-room management, resource mailboxes and federated calendar sharing, and the business plans bundle Word, Excel, PowerPoint and Outlook for desktop, web and mobile, Teams, and 1 TB of OneDrive per user. We found no public information on room-booking approval, delegated calendar access or in-browser co-editing, so I hold it just under the top band.
Proton for Business
Shared calendars with availability, invitations from the inbox, browser co-editing of documents and spreadsheets, Drive storage, Meet with 100 to 250 participants and apps across desktop, iOS and Android make a real bundle. We found no public information on CalDAV or CardDAV sync, Outlook calendar sync, room and resource booking, or tasks.
Security, encryption & compliance archiving
Microsoft 365 Business
The retention and legal-hold side is audit-grade: retention labels and policies across mailboxes, Teams and SharePoint, up to 50 holds per mailbox, records with proof of disposition for up to seven years, content search, plus S/MIME signing and encryption, multi-engine anti-malware and deleted mailbox and item recovery. We found no public information on certifications such as ISO 27001 or BSI C5 with their scope, enforced two-factor sign-in, encryption at rest, GoBD archiving or a transparency report on authority requests.
Proton for Business
End-to-end and zero-access encryption where the provider states it cannot decrypt content, PGP support, enforced two-factor with Sentinel, retention rules, a Swiss-only disclosure position, ISO 27001 with auditor and accreditation named, SOC 2 Type II and audited open-source apps. We found no public information on GoBD-compliant archiving, legal hold or eDiscovery, which matters to my Austrian clients.
Administration, identity & partner management
Microsoft 365 Business
For my own tooling this is strong: the Microsoft 365 and Exchange admin centres, remote PowerShell, the Graph API with SDKs to provision users, groups and Teams, usage reports and security alerts, and full Microsoft Entra ID integration with conditional access, identity protection and access-lifecycle governance. We found no public information on reseller or multi-tenant partner accounts for managing several customer organisations, audit-log export, SCIM provisioning or support response times — exactly the gaps that hurt a six-person shop with forty clients.
Proton for Business
Three granular admin roles with a per-area permission matrix, SAML single sign-on with Okta and Entra ID, a documented SCIM 2.0 API, an exportable activity monitor, 24/7 chat with phone from six users, and a 99.95% SLA with service credits. We found no public information on mobile device policies with remote wipe or partner and reseller accounts for managing several customer organisations, which is what my service business runs on.
Migration, open standards & exit
Microsoft 365 Business
Getting mail in is documented end to end: cutover up to 2,000 mailboxes, staged and hybrid migration with coexistence for gradual moves, IMAP from Gmail and other systems (mail folders only), a PST import service by network upload or drive shipping, cross-tenant moves, plus FastTrack and partner options. Exit is stated too — cancellation via the admin centre deletes all associated data, with a 7-day right of withdrawal — and Exchange Server remains available as a self-hosted edition; we found no public information on organisation-wide export by the admin in open formats.
Proton for Business
Easy Switch imports mail and contacts with free guided support, calendars import, apps are open source, and mail exports to EML and MBOX via the export tool or Bridge with Thunderbird, with deletion on cessation stated in the DPA. MBOX import needs a Thunderbird workaround in batches, and we found no public information on organisation-wide admin export, ICS or vCard export, or coexistence during a move.
European sovereignty
Microsoft 365 Business
The EU Data Boundary pages commit Microsoft to storing and processing Customer Data for Microsoft 365 tenants signed up in the EU or EFTA inside a boundary with named datacentre countries including Austria, Germany and Switzerland. But the parent company sits in Redmond, Washington, limited transfers outside the boundary continue in stated circumstances, and we found no public information on subprocessors, a published data processing agreement or an EU contracting entity — for my Austrian clients that is a boundary, not full sovereignty.
Proton for Business
Proton AG in Geneva with data centres exclusively in Europe, an EU representative in Luxembourg, a published DPA restricting transfers to Switzerland, the EU and adequacy countries, subprocessors listed with locations, and ISO 27001. Support and payment run through named processors in the United States, Macedonia and Taiwan, and the hosting infrastructure itself is not named, so the chain is documented but not European end to end.
Pricing transparency
Microsoft 365 Business
Business Basic at 6,07 € per user per month with annual billing, Business Standard with Copilot Business at 20,36 € and Business Premium with Copilot Business at 27,73 € are published with storage per plan, VAT treatment ("Preise zzgl. MwSt."), trial conditions and a 7-day withdrawal right, and shared and room mailboxes need no subscription. We found no public information on add-on prices for archiving or extra storage, a monthly-billing price for comparison, or minimum users — so I cannot compute a client's full year cost from these pages alone before quoting.
Proton for Business
Workspace Standard at €12.99/user per month with 1 TB and Premium at €19.99/user per month with 3 TB, monthly figures shown alongside, annual amounts of €155.88 and €239.88 every 12 months, VAT treatment with reverse charge on business plans, and a 30-day money-back guarantee. The Scribe add-on and extra aliases carry no public price, minimum users are not stated, and enterprise is a custom quote.
Sovereignty, side by side
Dimension
Microsoft 365 Business
Proton for Business
Legal entity
Not determined
Not determined
Hosting location
Not determined
Not determined
Hosting options
Not determined
Not determined
Open source
Not determined
Not determined
Data processing agreement
Not determined
Not determined
Transfer impact assessment
Not determined
Not determined
Facts, side by side
Only facts both products carry under the same definition — anything else would not be a fair row.
Questions about Microsoft 365 Business and Proton for Business
Which is better, Microsoft 365 Business or Proton for Business?
As of 6 Nov 2026, the panel rates Proton for Business higher: 3.5/5 against 3/5. Weighted by what each judge cares about, 4 of the 6 judges pick Microsoft 365 Business and 2 pick Proton for Business. Which one fits depends on the criteria that matter to you; the table on this page shows both side by side, and each judge’s reading has its own page. Both were scored by the same AI bench under the same rubric, from public evidence only, as the methodology describes.
Is Microsoft 365 Business or Proton for Business European?
Microsoft 365 Business is not European by provenance (Rest of world). Proton for Business is European (UK / wider Europe). Provenance is read from each company’s own legal pages: who builds it and who owns it.