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Mailcow — system requirements

Self-hosted groupware mail server bundle with webmail, ActiveSync, antivirus, and antispam. · website · repository

Minimum RAM
6 GB
“6 GiB + 1 GiB swap (default config)”
Scope: Minimum system resources table, mailcow: dockerized general install, default configuration (ClamAV antivirus and Flatcurve/FTS indexing both enabled) · official source · retrieved 2026-08-30
Recommended RAM
8 GB
“8 GiB RAM are recommended for ~5 to 10 users.”
Scope: Recommended for small installations with roughly 5-10 mailbox users (official RAM usage examples section, distinct from the general minimum) · official source · retrieved 2026-08-30
No official figure published for: minimum CPU cores, recommended CPU cores
The Minimum System Resources table states only a clock-speed figure ("CPU: 1 GHz"), not a core count, so no cpu_min_cores/cpu_rec_cores value can be sourced without inventing units the docs don't state (Defect Class #1).
We publish nothing we can't source. Evidence of the gap.

External services

The official docker-compose.yml wires a mariadb:10.11 container as mailcow's SQL backend; not optional or swappable in the official compose.

The official docker-compose.yml wires a redis:7.4.10-alpine container used as mailcow's cache; not optional or swappable in the official compose.

The official docker-compose.yml wires a memcached:alpine container used by Dovecot; not optional or swappable in the official compose.

Container

Image: ghcr.io/mailcow/postfix:3.10.12-1 · compressed size (amd64): 110 MB · architectures: amd64, arm64 · source, retrieved 2026-08-30

Mailcow ships as an 18-container stack (postfix, dovecot, sogo, nginx, php-fpm, mariadb, redis, memcached, clamav, rspamd, and more). No single container is named “mailcow”; postfix (the SMTP transfer engine) is shown here as the representative image, consistent with the project's core-identity convention for bundled apps (see Wazuh), but this size covers only that one container, not the whole stack's footprint.

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