SOGo workers and concurrent mailbox connections materially increase RAM usage.
Teams with many mobile clients.mailcow-Hardwareanforderungen: RAM, CPU, Mail-Speicher & Docker
Planen Sie mailcow-Hardware anhand der offiziellen Mindestanforderungen von 6 GiB RAM plus 1 GiB Swap, einschließlich Mail-Speicher, DNS und Ports, und beachten Sie wichtige Einschränkungen bei der ZimaOS-Unterstützung.
mailcow requirements at a glance
mailcow has a clear memory floor and strong platform requirements. Its upstream documentation explicitly says not to install it on Synology/QNAP or any NAS, OpenVZ, LXC or other container platforms.
- RAM minimum
- Official minimum: 6 GiB RAM plus 1 GiB swap with the default configuration.
- Private-use guidance
- Official docs say 6 GiB + 1 GiB swap is fine for most private installations and recommend 8 GiB for about 5–10 users.
- Larger example
- A company with 15 ActiveSync phones and about 50 concurrent IMAP connections should plan 16 GiB RAM.
- CPU
- Official minimum CPU frequency: 1 GHz. Workload depends on antivirus, FTS, SOGo and active connections.
- Platform warning
- Upstream explicitly says not to install mailcow on any NAS or other container platform; supported targets include full Linux hosts/VMs.
- Best Zima approach
- For Zima hardware, use a supported Linux VM rather than direct mailcow containers on ZimaOS if production reliability/support matters.
From official requirements to the right setup
For mailcow, platform compatibility is as important as RAM and CPU.
-
Official requirements
Meet the official minimum of 1 GHz CPU, 6 GiB RAM and 1 GiB swap for the default configuration.
-
Confirm your needs
Do not treat direct ZimaOS container deployment as upstream-supported: mailcow explicitly warns against NAS platforms and other container platforms.
-
Leave room to grow
Plan a public hostname, correct forward/reverse DNS, required mail ports and enough mail storage before installation.
-
Run it on ZimaOS
If using Zima hardware, prefer a full supported Linux VM and install mailcow there; use direct ZimaOS Custom App only as an unsupported experiment, not as the recommended production topology.
Check every playback client
- 6 GiB+ RAM
- 1 GiB+ swap
- Public/static IP
- Forward/reverse DNS
- Mail ports available
- Mailbox storage
- Antivirus/FTS enabled
- Backup strategy
Official minimum requirements
mailcow's current prerequisite page publishes explicit minimum memory/CPU requirements and a strong host-platform warning.
The official resource floor is 1 GHz CPU, 6 GiB RAM and 1 GiB swap. Direct NAS/container-platform deployment is explicitly unsupported upstream.
| Requirement | Official minimum | What this supports |
|---|---|---|
| CPU minimum | 1 GHz | Current official minimum. |
| RAM minimum | 6 GiB | Default configuration. |
| Swap minimum | 1 GiB | Default configuration. |
| 5–10 users | 8 GiB RAM recommended | Official guidance. |
| 15 EAS phones + ~50 IMAP | 16 GiB RAM | Official sizing example. |
| Unsupported platforms | Any NAS, OpenVZ, LXC or other container platforms | Explicit upstream warning. |
When to upgrade your hardware
mailcow should scale when SOGo/ActiveSync, full-text search, antivirus or mailbox concurrency consumes the available memory.
ActiveSync/IMAP concurrency grows
ClamAV and FTS consume memory
Mailbox data and backups grow
mailcow specifically calls out ClamAV and full-text search as RAM-hungry components.
Default/full-feature deployments.Mail storage, indexes and retained backups become the long-term capacity driver.
Long-running mail servers.Plan hardware growth with confidence
Scale mailcow by adding memory, mail storage and a supported host topology.
Use a full Linux VM instead of direct NAS containers
This aligns with mailcow's upstream platform support model.
Run a supported VM on suitable Zima hardware rather than direct ZimaOS containers.Use 16 GB for busier groupware use
Matches the upstream example for 15 ActiveSync phones and about 50 concurrent IMAP connections.
ZimaBoard 2 1664 or ZimaCube 2 Pro.Use SSD-backed mail/index storage
Mailbox indexes, FTS and database services benefit from reliable low-latency storage.
Use NVMe/SSD with the VM or underlying storage pool.Use multi-drive storage for mailbox retention/backups
Mail data and backup history may justify a larger storage platform.
ZimaCube 2 Pro.Can it run on ZimaOS?
mailcow is not a good direct ZimaOS container target: upstream explicitly says not to install mailcow on any NAS or other container platform. The Custom App path below should be treated as unsupported experimentation only.
Custom install mailcow in ZimaOS
Technically possible to adapt the Docker stack, but upstream explicitly does not support NAS/container-platform installations. Prefer a full supported Linux VM for real mail service.
Custom install mailcow in the ZimaOS app ↗Follow mailcow's supported-host requirements
Official prerequisites support full Linux hosts and full virtualization, while rejecting NAS/container platforms such as Synology/QNAP, OpenVZ and LXC.
Review mailcow host requirements ↗Use a VM when running on Zima hardware
A full Linux VM gives mailcow the host/networking model its documentation expects while keeping it on your Zima hardware.
Review ZimaOS virtualization options ↗Choose Zima hardware for mailcow
For mailcow, choose hardware to run a supported Linux VM with enough RAM and storage rather than treating ZimaOS direct containers as the recommended path.
Is this a private mail server or a busier groupware deployment?
Private/small deployment
Use at least 16 GB host RAM so the VM can receive 6–8 GiB while leaving room for ZimaOS.
- Practical hostZimaBoard 2 1664
More ActiveSync/IMAP users and mail storage
Use stronger compute, 16 GB+ host memory and expandable storage.
- Higher-headroom platformZimaCube 2 Pro
mailcow explicitly warns against NAS/container-platform deployment. These Zima recommendations assume mailcow runs inside a suitable full Linux VM.
| Zima hardware | Best for | Example workload | Core configuration | Recommended boundary | Next step |
|---|---|---|---|---|---|
| ZimaBoard 2 1664 | Small private mailcow VM deployments. | Full Linux VM with mailcow near the official small/private memory profile. |
|
16 GB host RAM must cover both the VM and ZimaOS; direct ZimaOS mailcow containers remain unsupported upstream. | Get Now |
| ZimaCube 2 Pro | Busier mailcow VM deployments and more storage. | Full Linux VM, more groupware connections, mail/index storage and backups. |
|
16 GB matches an upstream larger-use example but whole-host overhead reduces VM-available RAM; consider workload carefully. | Get Now |
What the Press Says
Highlights from trusted reviewers worldwide.
“ZimaCube 2: Not just another NAS, tested with 25TB storage, local AI agents, 4K transcoding, and real homelab workflows.”Read full review
“The ZimaBoard 2 is a compact x86 server board that can be turned into a mini NAS, home server, media box, or self-hosting hub.”Read full review
“ZimaCube 2: A modern, high-performance NAS with plenty of room to grow—built for users who want more than basic storage.”Read full review
“Coverage focused on ZimaCube 2's open hardware foundation, no monthly fee, and self-hosting flexibility.”Read full review
Loved by the Community
Stories and reviews from people who build with Zima every day.
★★★★★
Zima Blade Little yet Powerful
Maybe I am not digital natives but I live with PCs since 12 years old in 1984 when IBM PC clone come to my home. Many years have passed and many operating system I've tried. For me Zima blade and CasaOS was a quantum leap for home PC enthusiast and server lab machine to make me stay curious and relevant for this era.
★★★★★
Very good!!
I use ZimaCube Pro as 5th Proxmox cluster node. It runs several VMs and containers, including a VM with GPU passthrough to run a self-hosted LLM. A specific LXC container runs a Samba server for NAS capabilities using four of six RAID 6 SATA HDDs with ZFS.
★★★★★
Great innovation for mini server!
It is very useful and makes a powerful mini server for many purposes, including university and college students in engineering and electronics. Thank you so much for making this server.
★★★★★
Avaliação ZimaBoard 2
Construí um servidor de uso pessoal. O desempenho está muito bom e funciona perfeitamente onde quer que eu esteja. A surpresa é não dependermos de grandes estruturas para termos nosso próprio servidor de dados. Como iniciante, estou gostando bastante do ZimaOS, pois ele é simples e eficiente.
Frequently asked questions
These answers cover mailcow RAM, CPU, swap, NAS support, storage and ZimaOS deployment.
How much RAM does mailcow need?
Official minimum is 6 GiB RAM plus 1 GiB swap for the default configuration.
How much RAM is recommended for 5–10 mailcow users?
mailcow's docs recommend 8 GiB RAM for roughly 5–10 users.
How much CPU does mailcow need?
The official minimum CPU frequency is 1 GHz.
Can I run mailcow directly on a NAS?
Upstream explicitly says not to install mailcow on Synology/QNAP or any NAS, OpenVZ, LXC or other container platforms.
Why does mailcow need so much RAM?
It bundles webmail/groupware, ActiveSync, antivirus, antispam, full-text search, MariaDB, Redis, MTA/MDA and other services.
Does mailcow need a GPU?
No dedicated GPU is required.
Can I run mailcow on Zima hardware?
Yes, but the upstream-compatible approach is a full Linux VM rather than direct containers on the ZimaOS NAS host.
What affects mailcow storage needs?
Mailbox size, indexes, attachments, retention and backups dominate storage.
What sources informed this mailcow hardware guide?
The guide uses mailcow's current system-prerequisite documentation and current Zima product pages.
