Rspamd
Rspamd 4.3 fixes SPF evaluation order and rejects weak DKIM keys, with results that change.
Comparison · Comms
mailcow vs Fonoster
A side-by-side editorial comparison of mailcow and Fonoster — release velocity, themes, recent moves, and the top alternatives to consider.
mailcow vs Fonoster: at a glance
What is mailcow?
mailcow's November release patches an admin RCE and reworks sync jobs.
mailcow ships named monthly releases with lettered revisions, mostly to pull in upstream security fixes for SOGo, Nginx, Redis, Unbound and Rspamd. The November release goes further: it fixes a remote code execution flaw reachable by admins and domain admins, adds mailbox groups, and reworks imapsync so sync jobs reference a separate source. It also caps request bodies at 64 MB, which breaks large SOGo and ActiveSync mail unless NGINX_MAX_BODY_SIZE is raised.
What is Fonoster?
Fonoster now cleans up deleted workspaces and stops exposing stored secrets.
Fonoster ships minor versions almost daily. v0.51 to v0.53 added Anthropic, Google and Groq models, TTS voice choice and one-switch call recording. From November 10, v0.54 to v0.56 added branded emails, legal pages, webhook event lookups and API key rotation, and v0.57 returns secret values only to API keys, cancels a deleted user's plan, and ends a deleted workspace's calls and resources.
mailcow vs Fonoster: editorial side-by-side
mailcow
5.0COMMS
mailcow's November release patches an admin RCE and reworks sync jobs.
◆ Current state
mailcow ships named monthly releases with lettered revisions, mostly to pull in upstream security fixes for SOGo, Nginx, Redis, Unbound and Rspamd. The November release goes further: it fixes a remote code execution flaw reachable by admins and domain admins, adds mailbox groups, and reworks imapsync so sync jobs reference a separate source. It also caps request bodies at 64 MB, which breaks large SOGo and ActiveSync mail unless NGINX_MAX_BODY_SIZE is raised.
◆ Where it's heading
The monthly security cadence holds, but recent releases carry more of mailcow's own features and API changes alongside the upstream bumps. Breaking changes now come with explicit migration steps, which suggests the API is being cleaned up for integrators.
◆ Prediction
Expect the promised RCE advisory details next week and a lettered revision within weeks to address fallout from the sync job API and body-size changes.
Fonoster
7.5COMMS
Fonoster now cleans up deleted workspaces and stops exposing stored secrets.
◆ Current state
Fonoster ships minor versions almost daily. v0.51 to v0.53 added Anthropic, Google and Groq models, TTS voice choice and one-switch call recording. From November 10, v0.54 to v0.56 added branded emails, legal pages, webhook event lookups and API key rotation, and v0.57 returns secret values only to API keys, cancels a deleted user's plan, and ends a deleted workspace's calls and resources.
◆ Where it's heading
After a quick run of voice-AI options, Fonoster has turned to what a hosted service needs before paying customers rely on it: legal pages, billing correctness, webhook debugging and account deletion that actually removes data. The cadence stays daily and the changes stay incremental.
◆ Prediction
More account and billing lifecycle work is likely next, since v0.57 adds a billing test case and deletion rules in the same release.
Alternatives to mailcow and Fonoster
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 Fonoster.
Twilio
Twilio's voice AI stops cutting callers off mid-sentence, using its own turn-taking model.
Salesmsg
Salesmsg adds call-back requests and a one-click Emergency Stop for all outbound texts.
Element
Element 1.12.35 follows the call picture-in-picture release with one desktop storage fix.
Krisp
Krisp moves call transcripts and live captions to cloud transcription in KrispCX 2.84.4.
Misskey
Misskey 2026.11 ships: a leaner start script, and Node.js 22 no longer boots.
See all mailcow alternatives → · See all Fonoster alternatives →
Recent activity from mailcow and Fonoster
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 3d agoFonosterv0.57: secrets locked to API keys, full cleanup on account deletion
- 3d agoFonosterv0.56: webhook event bodies visible, API key regenerate becomes rotate
- 3d agoFonosterFonoster v0.55 shows the event each webhook delivery sent
- 3d agoFonosterFonoster v0.54.1 stops gather cutting off early answers
- 3d agoFonosterFonoster v0.54 adds branded emails and legal pages
- 5d agoFonosterFonoster v0.53 adds one-switch call recording and credit usage
- 9d agomailcowMoovember 2026: admin RCE fix, mailbox groups, imapsync rework
- 23d agomailcow🎃🐮 Mooctober 2026 | Security Update: PHP 8.2.35, SOGo 5.12.12 & Nginx 1.30.6
- 1mo agomailcow2026-09a: Rspamd 4.2.1 and postfix-tlspol bumps
- 1mo agomailcow🍂🐮 Mootember 2026 | Unbound 1.26.1, SOGo 5.12.11 & Redis 7.4.11
- 2mo agomailcow🏖️🐮 Mooly 2026 | Postfix 3.10.12, Rspamd 4.1.0 & Nginx 1.30.3 - Revision B
- 3mo agomailcow🏖️🐮 Mooly 2026 | Postfix 3.10.12, Rspamd 4.1.0 & Nginx 1.30.3 - Revision A
Frequently asked questions
What is the difference between mailcow and Fonoster?
They serve adjacent needs but don't currently overlap on shipped themes. Fonoster is currently shipping more aggressively (velocity 7.5 vs 5.0), 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 Fonoster?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Fonoster is currently shipping more aggressively (velocity 7.5 vs 5.0), 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 Fonoster?
Top Fonoster alternatives in Comms are ranked by recent ship velocity. Browse the "Fonoster alternatives" section above for the current picks, or visit /alternatives/fonoster for the full list with editorial commentary on each.