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Business Email & Office Suites

grommunio

EU-Made Report an error

Panel rating · 6 judges · How to read the stars

Category median

Sovereignty: not determined

0–5 in half steps. 5 means the rubric's top anchor is met on the evidence.

by grommunio GmbH · grommunio.com

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Add ?theme=dark to the image address for dark backgrounds. The badge shows the category and the month of the latest evaluation, and EU-Made where that is the product’s provenance. It never shows a score.

grommunio at a glance

Vendor
grommunio GmbH
Headquarters
Not stated on the vendor’s pages as of 5 Nov 2026
Data hosting
Not stated on the vendor’s pages as of 5 Nov 2026
Free plan
Yes, per the vendor’s own page source, captured 5 Nov 2026
Panel verdict
The AI panel rates grommunio 3.5/5, the mean of 6 judges. grommunio, an open-source Exchange replacement from grommunio GmbH of Vienna, scores between 5 and 8 across the seven criteria. how scores are made
As of
Vendor pages captured 5 Nov 2026; evaluated by the panel 6 Nov 2026. all sources

grommunio alternatives, European ones first →

Read this page as one judge. Each weighs the same scores by what they care about.

The Skeptic

Weighted verdict

Has seen "hosted in Germany" from a provider whose spam filter and support desk sit in the United States, "Exchange-compatible" that meant IMAP with a calendar plug-in, and a first-year price of one euro that became seven. Asks which protocols Outlook really uses, whether the archive would survive a tax audit, what the certification actually covers — and how ten years of mail, calendars and contacts would leave.

Same scores as the panel view — this lens weights them the way this judge cares.

Scored by The Skeptic

Panel median The Skeptic This judge’s scores over the panel median. Each label opens its reasoning below.
Scores per criterion, in stars out of 5
Criterion Panel median The Skeptic
Mail, domains & deliverability 3.5 of 5 3.5 of 5
Calendar, contacts & office apps 4 of 5 4 of 5
Security, encryption & compliance archiving 3 of 5 3 of 5
Administration, identity & partner management 4 of 5 3.5 of 5
Migration, open standards & exit 4 of 5 3.5 of 5
European sovereignty 4 of 5 3.5 of 5
Pricing transparency 3 of 5 3 of 5

Mail, domains & deliverability

How this is scored

How well the mailbox itself works: custom domains and their DNS set-up, aliases, catch-all, shared and functional mailboxes, distribution lists, mailbox and attachment size limits, IMAP, POP3, SMTP and Exchange ActiveSync or MAPI for Outlook, web and mobile apps, spam and malware filtering, SPF, DKIM, DMARC and MTA-STS, out-of-office and server-side rules, send limits, and the delivery reputation of the sending infrastructure. A self-hosted groupware is judged on the mail server it ships; a suite whose mail app is only a client for another server scores at the level of that client.

0 — No mailbox at all; a product that only sends transactional mail or only reads another provider's mail without a server of its own or a documented one to pair it with.

3 — Mailboxes on a custom domain with IMAP and SMTP and a webmail; aliases, shared mailboxes, filtering and DKIM or DMARC are basic or not described.

5 — Several custom domains with a documented DNS set-up, aliases and distribution lists, shared or functional mailboxes, IMAP and SMTP plus mobile apps, spam and malware filtering, SPF and DKIM signing, mailbox size per plan stated, server-side rules and out-of-office replies.

8 — Exchange ActiveSync or native Outlook (MAPI) support, DMARC reporting and MTA-STS or DANE, catch-all and plus addressing, delegated access and send-as, quarantine an admin can review, send and attachment limits stated, and the deliverability of the outbound infrastructure documented.

10 — A mail platform a large organisation runs on: every protocol above with feature parity stated per client, inbound and outbound gateways configurable, journaling, DANE and MTA-STS enforced, delivery monitoring and bounce analysis for admins, and mail flow documented end to end.

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The Skeptic

Outlook for Windows connects natively over MAPI/HTTP with nothing to install on the client, and EWS, Exchange ActiveSync, IMAP/POP3/SMTP and CalDAV/CardDAV are all listed; Postfix ships as the integrated MTA, Rspamd as the antispam engine with its own admin view, and domains, per-user send/receive/storage quotas and send-as permissions are managed from the admin console. I hold it back because the vendor's own knowledge base states that sending from a secondary alias address is off by default, and we found no public information on DKIM or DMARC signing, MTA-STS, catch-all handling, or stated message and attachment size limits. 2 3 10 11 16

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Calendar, contacts & office apps

How this is scored

What the office plans and writes with: shared and team calendars, free/busy lookup, meeting invitations across providers, room and resource booking, shared address books and a company directory, CalDAV and CardDAV or ActiveSync for phones, Outlook calendar sync, tasks, online office documents with co-editing, file storage that comes with the suite, video meetings and chat inside the bundle, and the desktop and mobile apps.

0 — Mail only, with no calendar or contacts of any kind.

3 — A personal calendar and address book in the webmail; sharing, resources, sync protocols and office apps are basic or not described.

5 — Shared calendars and address books, meeting invitations with free/busy lookup, CalDAV and CardDAV or ActiveSync sync to phones and desktop clients, a company-wide address book, tasks, and either online office documents or a documented integration with an office suite.

8 — Room and resource booking with approval, delegated calendar access, Outlook calendar and contacts sync documented, co-editing of documents and spreadsheets in the browser, file storage with sharing, video meetings in the bundle, and apps for desktop, iOS and Android.

10 — A full office suite that replaces Microsoft 365 for a whole organisation: every function above with Microsoft file formats edited without loss, scheduling across organisations, resource planning, offline editing, an accessible interface stated against a standard, and feature parity across web, desktop and mobile documented.

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The Skeptic

Rooms book directly into their calendars and decline conflicting times, delegation for assistants and three levels of calendar permissions are documented, and CalDAV/CardDAV plus ActiveSync cover phones, with browser co-editing of Word, Excel and PowerPoint via OnlyOffice, Nextcloud-based file storage, WebRTC video meetings and chat apps for iOS, Android, Windows, Mac and Linux. I stop below the top because Outlook calendar and contacts sync is implied by the native MAPI connection rather than spelled out, and we found no public information on accessibility standards or feature parity across web, desktop and mobile. 2 3 12 13

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Security, encryption & compliance archiving

How this is scored

How mail and documents are protected and kept: TLS enforced in transit, encryption at rest, end-to-end encryption or S/MIME and PGP, who at the provider can read a mailbox, two-factor authentication and passkeys, phishing, malware and account-takeover protection, audit-proof archiving that meets GoBD, retention policies and legal hold, eDiscovery, backups and restore of deleted mail, a transparency report on authority requests, and certifications (ISO 27001, BSI C5, SOC 2) with their scope.

0 — No security information of any kind; no encryption, two-factor sign-in or archiving stated.

3 — Encrypted connections and a password login; encryption at rest, two-factor sign-in, archiving and certifications are basic or not described.

5 — TLS in transit and encryption at rest stated, two-factor authentication, spam, phishing and malware protection, restore of deleted mail for a stated period, archiving offered (built in or as an add-on), and a certification such as ISO 27001 stated for the data centres or the service.

8 — End-to-end encryption, S/MIME or PGP supported, GoBD-compliant archiving documented, retention policies and legal hold, enforced two-factor or passkeys for all users, a transparency report on authority requests, and certifications such as ISO 27001 or BSI C5 published with their scope and auditor.

10 — Security that holds up in an audit of a regulated organisation: zero-access or customer-held keys where the provider cannot read mail, eDiscovery, tamper-proof archive with documented verification, every certification published with its report or attestation available, independent security audits or open-source code reviewed, and incident disclosure documented.

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The Skeptic

S/MIME is on by default and OpenPGP decrypts in the browser with passphrase-protected keys and no unencrypted drafts saved while encrypting — a serious implementation — alongside multi-factor sign-in via TOTP, FIDO2 or your identity provider, and an archive built on Piler storing deduplicated, encrypted copies with full-text search, 2FA and audit logs. But the vendor itself writes that what must be retained and how evidential value is preserved are the operator's legal questions; we found no public information on GoBD-compliant archiving, retention policies, legal hold or a transparency report, and no certification such as ISO 27001 or BSI C5 appears on the captured pages. 3 4 6 14 15

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Administration, identity & partner management

How this is scored

How an IT team or an IT service provider runs it: an admin console for users, groups, mailboxes and domains, admin roles, single sign-on (SAML or OpenID Connect), sync with Active Directory, Entra ID or LDAP, SCIM provisioning, mobile device policies and remote wipe, audit logs of admin and user actions, usage reports, a documented API for provisioning, multi-tenant or reseller accounts for partners managing several customers, and the support channels and response times per plan.

0 — No administration; one login per mailbox and nothing managed centrally.

3 — A web console to add mailboxes and aliases; roles, single sign-on, directory sync and audit logs are basic or not described.

5 — An admin console for users, groups, mailboxes and domains, admin roles, two-factor sign-in enforceable by the admin, password policies, a documented API or command line for provisioning, an activity or audit log, and business support by phone or ticket stated per plan.

8 — Single sign-on (SAML or OpenID Connect), Active Directory, Entra ID or LDAP sync, SCIM provisioning, mobile device policies with remote wipe, audit logs exportable, delegated administration, partner or reseller accounts that manage several customer organisations, and support response times stated.

10 — Administration that scales across many organisations: every setting reachable by API with parity stated, granular role scopes, policies by group, logs streamed to a SIEM, white-label partner offerings with separate billing, and an SLA with service credits published.

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The Skeptic

An OpenAPI 3.0 REST API and a full command-line client sit beside the browser console, with roles from SystemAdmin down to DomainAdmin and OrgAdmin, LDAP and Active Directory synchronisation, SAML/OIDC and Kerberos single sign-on, mobile device management with remote wipe, multi-tenancy for hosting several isolated organisations, and more than 200 certified partners. We found no public information on SCIM provisioning, exportable audit logs or concrete response times — 'enhanced response' on the Business plan and a 'negotiated SLA' at Enterprise are not numbers an IT department can hold anyone to. 1 3 6 7 16 17

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Migration, open standards & exit

How this is scored

How the organisation gets in and out: migration from Exchange, Microsoft 365, Google Workspace or another IMAP provider with a documented tool or service, mail, calendars and contacts carried over, coexistence during a move, standard protocols (IMAP, CalDAV, CardDAV, JMAP, open document formats) rather than proprietary ones, export of a mailbox and of the whole organisation in standard formats (mbox, EML, PST, ICS, vCard), open-source code or a self-hosted edition, what happens to data when the contract ends, and how domains and DNS are handed back.

0 — No way to bring mail in or take it out; a proprietary store with no IMAP access or export.

3 — IMAP access to mail; a migration path, calendar and contacts export and the end-of-contract handling are basic or not described.

5 — A documented migration from Exchange, Microsoft 365 or Google (a tool, an import or a service), mail, calendars and contacts imported, IMAP, CalDAV and CardDAV or ActiveSync access, export of mail, calendars and contacts in standard formats, and the deletion of data after the contract ends stated.

8 — A migration service or tool that moves whole organisations with calendars and permissions, coexistence with free/busy during the move, open document formats supported natively, export of the whole organisation by the admin, an open-source code base or a self-hosted edition, and a data return period after cancellation stated.

10 — An exit that costs nothing but time: every record exportable in open formats with the method documented, a self-hosted open-source edition with feature parity stated, migration in and out documented with the same tools, and a contractual data return and deletion with confirmation.

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The Skeptic

The Exchange migration is documented down to the shipped PowerShell script: PST export per mailbox, a two-pass mode for large cut-overs, resume files recording done and failed imports, and a final delta run after the DNS/MX switch; imapsync for any IMAP source, a Kopano/Zarafa tool carrying complete mailboxes with MAPI properties, and generic EML, ICS and VCF importers are listed, and the code base is published as 100% open source with a free community edition carrying the full feature set. We found no public information on whole-organisation export by the admin in standard formats, on whether folder permissions travel with the migration, or on data return and deletion after a contract ends. 2 3 4 18 19

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European sovereignty

How this is scored

Who the contracting entity and the parent company are, where mailboxes, calendars, contacts, documents and backups are stored and processed, who at the provider or its subprocessors can access them, and who the subprocessors are (data centres, spam filtering, support, payment, AI features). Independently sourced by the sovereignty pipeline. An EU data region offered by a non-EU parent is part of the chain, not the whole of it. A self-hosted or open-source edition the customer runs on its own European servers counts as the customer's chain, whatever the vendor's seat.

0 — Non-EU vendor and contracting entity, hosting unstated, subprocessors unnamed, and no data processing agreement offered.

3 — A privacy policy and a data processing agreement exist, but hosting location is unstated or non-EU and the subprocessors are not listed.

5 — EU hosting available and an EU contracting entity or EU representative, but parts of the chain (spam filtering, support, backups, AI features) run through non-EU providers or a non-EU parent without a stated safeguard.

8 — EU hosting on named infrastructure, EU contracting entity, subprocessors listed with their locations, a data processing agreement published, and security certifications (ISO 27001, BSI C5) stated — or a self-hosted edition documented that keeps every mailbox on the customer's own servers.

10 — Sovereign end to end and evidenced: European ownership, entity, hosting and every subprocessor, or a self-hosted open-source edition with no call home, data export and deletion documented, and certifications published with their scope rather than implied.

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The Skeptic

The legal notice puts grommunio GmbH in Vienna with a commercial register number and Austrian tax ID, and the privacy policy states plainly that customers or sales partners host the software, in which case grommunio processes no personal data at all — when you self-host, the chain is genuinely your own. But the priced plans route you to a 'certified European partner' without documenting where those mailboxes would sit, we found no public information confirming a published data-processing agreement or any certification such as ISO 27001 or BSI C5, and the only subprocessor the privacy policy names by location is the US-based newsletter tool MailChimp. 3 4 7 8 9

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Pricing transparency

How this is scored

Whether a buyer can compute the real annual cost from public pages alone: price per user or mailbox per tier, storage per user, what shared mailboxes, aliases and extra domains cost, which features (archiving, office apps, SSO, advanced security, more storage) cost extra, the first-year discount and the regular price after it, minimum users and term, monthly versus annual billing, and VAT.

0 — No public prices at all; every customer is a sales call.

3 — A starting price per user exists, but how cost scales with storage, users, add-ons or after the first year is unclear.

5 — Tiers are public with their price per user and main inclusions, but at least one commonly needed piece (archiving, extra storage, shared mailboxes, SSO, the price after the introductory period) is unpriced or "on request".

8 — Every tier priced publicly per user with storage, add-ons priced, the regular price after any introductory discount stated, minimum users and term stated, monthly and annual billing compared, and VAT treatment stated.

10 — Complete price computability: annual cost derivable for a given number of users, storage and add-ons, with every support, migration and archive fee and the cancellation and data-return terms published.

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The Skeptic

Four tiers carry public per-user monthly prices with minimum user counts — 'Basic €1.99 / user / month From 6 users', 'Plus €3.99', 'Business €5.49 From 50 users', Enterprise 'custom' from 1,000 users — beside a free community edition up to 5 users, a statement that all software features are included in every plan, and a calculator marked 'Austria, ex VAT'. I hold it back because billing period and contract term are not stated, the top tier is priced only on request, and the vendor's own comparison page calls the figures 'illustrative estimates … not a quote', while the cost a hosting partner would charge is not broken out. 3 7

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European sovereignty — proven facts

0 of 6 dimensions proven

Built only from facts shown on the vendor's own pages. A dimension we could not prove is left open, not scored as zero.

Hosting location Not determined — uncited Report an error
Hosting options Not determined ⚠ unverified — uncited Report an error
Open source Not determined ⚠ unverified — uncited Report an error
Data processing agreement Not determined — uncited Report an error
Transfer impact assessment Not determined — uncited Report an error

Questions about grommunio

Is grommunio European?

Yes. whats-best.ai classifies grommunio as EU-Made.

Where does grommunio store data?

Not stated on the vendor’s pages as of 5 Nov 2026.

Does grommunio have a free plan?

Yes. grommunio has a free plan, per the vendor’s page captured 5 Nov 2026.

What are the best alternatives to grommunio?

As of 6 Nov 2026, the panel rates Infomaniak kSuite (3.5/5), Nextcloud Hub (Groupware & Office) (3.5/5) and Proton for Business (3.5/5) highest among the other 14 Business Email & Office Suites products evaluated. Ratings that look equal are rounded to half stars; the order uses the unrounded rating, then the name. The highest-rated European alternative is Infomaniak kSuite (UK / wider Europe). Ratings are the AI panel’s opinion, formed from public evidence: how scores are made. The full list, with European products first: grommunio alternatives.

Where this could be wrong

What we left out

A claim that does not survive our checks costs us the claim, not the page. This is what was taken off this one.

Do you know more about grommunio? Tell us Report an error on this page

Sources (19)

The pages every claim on this page was read from — each one checked, dated, and kept verifiable.

  1. 1 Vendor homepage grommunio.com Checked 5 Nov 2026 Details →
  2. 2 Features page grommunio.com Checked 5 Nov 2026 Details →
  3. 3 Features page (Exchange alternative) grommunio.com Checked 5 Nov 2026 Details →
  4. 4 Security / trust page grommunio.com Checked 5 Nov 2026 Details →
  5. 5 Documentation docs.grommunio.com Checked 5 Nov 2026 Details →
  6. 6 Documentation (administration) docs.grommunio.com Checked 5 Nov 2026 Details →
  7. 7 Pricing page grommunio.com Checked 5 Nov 2026 Details →
  8. 8 Legal notice grommunio.com Checked 5 Nov 2026 Details →
  9. 9 Privacy policy grommunio.com Checked 5 Nov 2026 Details →
  10. 10 Mail, domains & deliverability — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  11. 11 Mail, domains & deliverability — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  12. 12 Calendar, contacts & office apps — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  13. 13 Calendar, contacts & office apps — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  14. 14 Security, encryption & compliance archiving — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  15. 15 Security, encryption & compliance archiving — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  16. 16 Administration, identity & partner management — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  17. 17 Administration, identity & partner management — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  18. 18 Migration, open standards & exit — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →
  19. 19 Migration, open standards & exit — found from sitemap docs.grommunio.com Checked 5 Nov 2026 Details →