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Comparison · Comms
mailcow vs opus
A side-by-side editorial comparison of mailcow and opus — release velocity, themes, recent moves, and the top alternatives to consider.
mailcow vs opus: at a glance
What is mailcow?
mailcow's release notes are almost entirely upstream security currency.
mailcow ships named seasonal releases with lettered revisions, and nearly every revision exists to pull in an upstream security fix - Redis, ClamAV, SOGo, Rspamd, nginx, unbound, Postfix. Revision B of the Mooly 2026 release updates Redis 7.4.10, ClamAV 1.4.6, and SOGo 5.12.10, adds minor web UI and nginx hardening, and removes a legacy DeltaChat sieve rule. The last release with genuinely new features was the March cut, which added forced 2FA, ACME DNS-01 challenges, and a passwordless autodiscover endpoint.
What is opus?
Opus put neural networks inside the codec, then pushed the sample rate to 96 kHz.
Opus is at 1.6.1, a small fix release on top of 1.6. The two releases that matter in this window are 1.5, which made the first extended use of machine learning in the encoder and decoder through Deep Redundancy and Deep PLC, and 1.6, which built on that with a wideband-to-fullband bandwidth extension module, 96 kHz support under the Opus HD name, and a 24-bit API. Between and around them sit build fixes and checksum-only patches.
mailcow vs opus: editorial side-by-side
mailcow
5.0COMMS
mailcow's release notes are almost entirely upstream security currency.
◆ Current state
mailcow ships named seasonal releases with lettered revisions, and nearly every revision exists to pull in an upstream security fix - Redis, ClamAV, SOGo, Rspamd, nginx, unbound, Postfix. Revision B of the Mooly 2026 release updates Redis 7.4.10, ClamAV 1.4.6, and SOGo 5.12.10, adds minor web UI and nginx hardening, and removes a legacy DeltaChat sieve rule. The last release with genuinely new features was the March cut, which added forced 2FA, ACME DNS-01 challenges, and a passwordless autodiscover endpoint.
◆ Where it's heading
For a self-hosted mail stack that bundles a dozen upstream components, keeping current with their CVEs is the product, and mailcow has organized its release cadence around exactly that. The pattern is consistent: a named release with some feature content every few months, then lettered revisions that are pure security currency plus small web UI escaping and validation fixes. The web interface is where mailcow's own code gets hardened - HTML escaping in quarantine views and sieve editors recurs across several revisions.
◆ Prediction
Expect the next entry to be another lettered revision carrying upstream updates, with the next named release likely bundling whatever feature work has accumulated since March.
opus
0.0COMMS
Opus put neural networks inside the codec, then pushed the sample rate to 96 kHz.
◆ Current state
Opus is at 1.6.1, a small fix release on top of 1.6. The two releases that matter in this window are 1.5, which made the first extended use of machine learning in the encoder and decoder through Deep Redundancy and Deep PLC, and 1.6, which built on that with a wideband-to-fullband bandwidth extension module, 96 kHz support under the Opus HD name, and a 24-bit API. Between and around them sit build fixes and checksum-only patches.
◆ Where it's heading
Opus is moving in two directions that would once have looked contradictory: reconstructing audio that was never transmitted, via ML-based redundancy and loss concealment at very low bitrates, and carrying far more of it, via 96 kHz and 24-bit paths. Both extend a codec whose IETF-standard core has been frozen for years, by adding layers around it rather than changing the bitstream everyone already decodes.
◆ Prediction
With 1.6.1 confined to minor fixes and the bandwidth-extension module newly landed, the next releases are likely to tune and optimize the existing ML modules rather than add another.
Alternatives to mailcow and opus
Other Comms products tracked by Sparkpulse, ranked by recent ship velocity. Each card links to a full editorial trajectory and lets you pivot into a head-to-head comparison with either mailcow or opus.
Proton Bridge
Proton Bridge spends its first release in ten weeks on crashes, memory bounds and dead code
Stalwart
Stalwart is chasing mail RFCs and its own storage layer at the same time
Mux
Every manual control Mux ships now arrives with a Robots workflow that does it for you
Netcore Cloud
Netcore's feed remains a demand-generation channel; ten entries, zero product releases.
Openfire
Openfire keeps its XMPP server current without changing what it is.
See all mailcow alternatives → · See all opus alternatives →
Recent activity from mailcow and opus
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 1d agomailcow🏖️🐮 Mooly 2026 | Postfix 3.10.12, Rspamd 4.1.0 & Nginx 1.30.3 - Revision B
- 20d agomailcow🏖️🐮 Mooly 2026 | Postfix 3.10.12, Rspamd 4.1.0 & Nginx 1.30.3 - Revision A
- 1mo agomailcow🏖️🐮 Mooly 2026 | Postfix 3.10.12, Rspamd 4.1.0 & Nginx 1.30.3
- 2mo agomailcowThird May revision: unbound CVE and nginx 1.30.2
- 3mo agomailcowSecond May revision: quarantine table HTML escaping
- 3mo agomailcowSOGo 5.12.8 covering four upstream security issues
- 7mo agoopusOpus 1.6.1 fixes minor issues found after 1.6
- 8mo agoopusOpus 1.6 adds 96 kHz audio and ML bandwidth extension ⚡
- 1y agoopusOpus 1.5.2 fixes builds and an AVX2 crash on Windows
- 1y agoopusOpus 1.5.1 fixes the meson build
- 1y agoopusOpus 1.5 brings machine learning into the encoder and decoder ⚡
- 3y agoopusOpus 1.4 retunes in-band FEC and adds Meson support
Frequently asked questions
What is the difference between mailcow and opus?
They serve adjacent needs but don't currently overlap on shipped themes. mailcow is currently shipping more aggressively (velocity 5.0 vs 0.0), with 0 editorial sparks in the last 30 days against 0. See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is mailcow better than opus?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. mailcow is currently shipping more aggressively (velocity 5.0 vs 0.0), with 0 editorial sparks in the last 30 days against 0. For your specific use case, the alternatives sections above list other Comms products to evaluate alongside.
What are the best alternatives to mailcow?
Top mailcow alternatives in Comms are ranked by recent ship velocity. Browse the "mailcow alternatives" section above for the current picks, or visit /alternatives/mailcow for the full list with editorial commentary on each.
What are the best alternatives to opus?
Top opus alternatives in Comms are ranked by recent ship velocity. Browse the "opus alternatives" section above for the current picks, or visit /alternatives/opus-codec for the full list with editorial commentary on each.