Sovereign Email Infrastructure
Secure Email Hosting in Germany
GDPR- and ISO 27001-compliant mailboxes on our own hardware in Frankfurt — from ten to ten thousand accounts, run 24/7 by open-source engineers. Built on Postfix and Dovecot, priced per mailbox.
GDPR & ISO 27001 compliant
BSI TR-03108 & TR-03182
Frankfurt, Germany — own hardware
99.9 % availability SLA
100 % open-source stack
Initial situation
Paying for a full suite when all you need is email
On 1 July 2026 Microsoft raised its business plan prices: Business Basic by 16.7 % ($6 → $7), Business Standard by 12 % ($12.50 → $14 per user/month, as of July 2026) — citing the integration of Copilot Chat. The AI surcharge applies whether you use it or not. For 100 mailboxes on Business Standard that is $16,800 per year for a bundle of apps — while the mail itself sits under US jurisdiction. If what your organization actually needs is reliable, compliant email, there is a leaner answer: open-source mail infrastructure on German hardware, priced per mailbox.
- Pay per mailbox — not per suite seat with AI features priced in
- German jurisdiction — Frankfurt DC or your own hardware, encryption at rest
- Open standards — IMAP, SMTP, S/MIME; every mail client keeps working
- Open source — Postfix, Dovecot, Rspamd; no license fees, no lock-in
The offer
What “Managed Email” means at Hostzero
We run mailboxes at every scale — ten to ten thousand
Updates & security patches handled
24/7 monitoring & deliverability care
Frankfurt DC, on-premise or hybrid
No lock-in — standard protocols, export anytime
Why teams move their email to us
Deliverability, Engineered
SPF, DKIM and DNSSEC configured correctly, AI-assisted filtering with Rspamd, virus scanning with ClamAV. Spam stays out of your inbox — and your mail stays out of other people's spam folders. Deliverability is monitored, not hoped for.
Compliance Without Paperwork
GDPR- and ISO 27001-compliant hosting aligned with BSI Technical Guidelines TR-03108 and TR-03182. Data stored exclusively in Frankfurt, encrypted at rest, with daily backups — 100 GB per mailbox included.
S/MIME Without User Effort
A server-side gateway signs and, where required, encrypts outgoing mail automatically. Certificates are managed centrally by administrators — employees change nothing in their clients. Built for public-sector and regulated communication.
Microsoft 365 vs sovereign email hosting — the honest comparison
| Criterion | Microsoft 365 | Hostzero Managed Email |
|---|---|---|
Cost model | Per user, per suite — AI features priced in since July 2026 | Fixed price per mailbox — email, nothing you don't use |
Scope | Full suite: Office apps, Teams, SharePoint | Email done properly — you pay only per mailbox |
Office & collaboration | Deep integration — Word, Excel, Teams in one subscription | Not our business — bring the tools you already use |
Data jurisdiction | US CLOUD Act applies | German law — Frankfurt DC or your premises |
Provisioning & scale | Instant, global, effectively unlimited | Ten to ten thousand mailboxes — new accounts in minutes, hardware growth in days |
Client choice | Outlook-first; IMAP available | Any standards client — IMAP/IMAPS, POP3, webmail, API |
Signing & encryption | Per-tenant configuration and add-ons | S/MIME gateway — server-side, centrally managed |
Backups | Shared responsibility — restore typically needs a third-party backup tool | Daily backups included |
Support | Ticket tiers, paid support plans | Direct engineer access |
Service models
From ten mailboxes to your own mail platform — pay for what you actually need
Every environment is sized individually — we are happy to talk to organizations of all sizes. All prices are net.
Managed Mailboxes
Dedicated Mail Infrastructure
S/MIME Signing Gateway
Server-side signing and encryption of outgoing mail with centrally managed certificates — no changes on employee devices. For public-sector and regulated communication. Price on request — also available for mail environments we do not host.
Request offerArchitecture
One stack — every component open source
Postfix
Proven mail transfer agent for reliable delivery — the workhorse of the internet's mail
Dovecot
Secure, high-performance IMAP and POP3 server — your mailboxes, served fast
Rspamd
Modern spam filtering with machine-learning support — tuned, not just installed
ClamAV
Integrated antivirus scanning and content filtering on every message
SPF, DKIM & DNSSEC configured per domain
Encryption at rest in Frankfurt
Daily backups, 100 GB per mailbox
Webmail, IMAP/POP3, Managesieve & API access
Which email setup fits?
Not every company should leave Microsoft 365
Stay on Microsoft 365
If your teams live in Word, Excel, Teams and SharePoint all day, email is one part of a suite you would license anyway — and the bundle remains a reasonable deal, price increases included. Leaving M365 just for the mailbox rarely pays off in that setup.
Hostzero Managed Email
When email itself must be compliant, sovereign and deliverable — public sector, regulated industries, system mail at scale — or when you simply refuse to pay a suite price with an AI surcharge for a mailbox. Open source, German jurisdiction, priced per mailbox.
Onboarding
From assessment to cutover — without losing a single message
Assessment
Mailbox inventory, domains, compliance requirements — and whether leaving your current provider makes sense at all
Setup
DNS, SPF/DKIM/DNSSEC, mailboxes, webmail — environment built and tested, in Frankfurt or on your hardware
Migration
Mailboxes sync via IMAP, domain by domain — your current provider stays live as fallback until cutover
Operation
Monitoring, patching, deliverability care — per your service model, up to 24/7 with SLA
Why teams choose Hostzero for email
We run mail infrastructure the way we run storage and Kubernetes: on our own hardware in Frankfurt, on open source, for organizations from ten to ten thousand mailboxes — and for ourselves.
15+ Years Open Source
Enterprise open-source experience — network security on Juniper/Linux, SELinux, and production infrastructure we run for ourselves and our customers.
Email Is Infrastructure, Not an App
Postfix and Dovecot run on the same Frankfurt platform our own systems depend on. Deliverability, DNS and encryption are engineering work — and it is ours, around the clock.
Direct Engineer Access
No ticket tiers, no middlemen — you talk to the people who run your mail servers.
Customer voice
In production at mavoo GmbH
mavoo GmbH runs its email and infrastructure on Hostzero — and talks directly to the engineers who operate it.
"We moved our mailboxes to Hostzero along with the rest of our infrastructure. Deliverability just works for our business email and system messages to our customers. When something needs attention, we talk to the engineer who runs it, not a ticket queue."
Rainer Barton, mavoo GmbH
FAQ
Frequently Asked Questions
Start now
Ready to own your email?
Talk to an engineer — 30 minutes, no sales pitch. Tell us your mailbox count and compliance requirements, and we will tell you honestly whether sovereign email hosting fits — or whether staying on Microsoft 365 is the right call for you.