VG
VENTUREGAPS
C

Cyrus IMAP

OPEN SRC

The complete, scalable, and open-source email, contacts, and calendar server.

VG SCORE
9.0

Product Details

PricingOpen Source
API✅ REST
Learning CurveSteep
Integrations13 available

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PROS & CONS

STRENGTHS

  • Enterprise-grade scalability and reliability proven in large installations.
  • Actively maintained with strong community and commercial support.
  • Extremely scalable and proven in large, demanding environments.

WEAKNESSES

  • Lacks a built-in webmail client, requiring integration with separate projects like Roundcube.
  • Steep learning curve; configuration is complex for non-experts.

KEY FEATURES

Unified Storage (Sieve)

Uses a single-store 'Sieve' backend for mail, calendar, and contact data.

Scalable Architecture

Designed for large-scale deployments with high concurrency and data volume.

High Scalability

Designed to handle massive mailboxes and high user loads efficiently.

CalDAV & CardDAV Support

Full support for calendar and contact synchronization via open standards.

WHO IS Cyrus IMAP BEST FOR?

System administrators at universities or large enterprises

They need a scalable, secure, and standards-compliant mail server to manage email, contacts, and calendars for thousands of users.

Developers and IT teams building custom email solutions

They require a robust, open-source platform with extensive protocol support (IMAP, CalDAV, CardDAV) to integrate email and scheduling into applications.

INTEGRATIONS

Apple MailSieveSOGoLDAP servers (e.g., OpenLDAP)PostfixDavMailK-9 MailCalDAV/CardDAV clientsOutlookThunderbirdZ-PushDovecotRoundcube

TECHNICAL DETAILS

LEARNING CURVE
STEEP — SIGNIFICANT ONBOARDING
API

REST

FIELD REPORTS (0)

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FINAL ASSESSMENT

APPROVED — WORTH YOUR MONEY