Best Self-Hosted Email Server tools by public signals

These picks are computed from scored public evidence. Use the openness column in the ranking to separate OSI-approved, source-available, open-core, proprietary, and unverified-license tools.

Use Case Rankings

Ordered by ToolVitals score, health, shipping, confidence, and then adoption as a tie-breaker.

# Tool Health Shipping Openness Stars Score Status
01 gromox
Groupware backend supporting mail and calendar protocols.
83 89 OSI-approved OSS 247 88 Active
02 Modoboa
Mail hosting made simple
81 87 OSI-approved OSS 3.5k 88 Active
03 Mailu
Self-hosted mail server stack packaged as Docker images.
85 82 OSI-approved OSS 7.4k 86 Active
04 KumoMTA
The first Open-Source high-performance MTA developed from the ground-up for high-volume email sending environments.
77 72 OSI-approved OSS 511 81 Active
05 Mox
modern full-featured open source secure mail server for low-maintenance self-hosted email
65 35 OSI-approved OSS 5.8k 61 Warning
06 Mail-in-a-Box
Mail-in-a-Box helps individuals take back control of their email by defining a one-click, easy-to-deploy SMTP+everything else server: a mail server in a box.
49 20 License unknown 15.4k 52 Critical
07 ViMbAdmin
Virtual Mailbox Administration
28 0 OSI-approved OSS 484 29 Critical