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Comparison · Comms

Maddy vs Slack

A side-by-side editorial comparison of Maddy and Slack — release velocity, themes, recent moves, and the top alternatives to consider.

Maddy vs Slack: at a glance

FeatureMaddySlack
SectorCommsComms, Collab
Velocity score0.06.3
Sparks · 30d01
Top themesmail-server, self-hosted, golang, zero-downtime-reloadagents, mcp, developer-platform, marketplace
Last editorial update1mo ago13d ago
WebsiteVisit →Visit →

What is Maddy?

A one-binary mail server learning to behave like production infrastructure.

maddy is an all-in-one SMTP and IMAP server written in Go, aimed at people who want a working mail host without assembling Postfix, Dovecot and a policy daemon themselves. The 0.9 line moved quickly — 0.9.0 through 0.9.5 between late March and late May — with the sequence following a recognisable shape: a feature release, an immediate patch for a broken integration, a security release, then cleanup. Configuration is directive-based, and much of the changelog concerns the behaviour of individual modules like auth.ldap, check.rspamd and check.dnsbl.

Read the full Maddy trajectory →

What is Slack?

Slack raises the Marketplace bar back to ten installs while the agent platform consolidates.

Slack's developer platform runs two tracks. The agent build-out has produced a spark roughly every two weeks since June — MCP client, a skills plugin targeting Claude Code and Cursor, and Slack Code — and now has a consolidation date attached: assistant_view is deprecated in February 2027, replaced by an Agent Sessions API. The second track is platform administration and tooling, and this window belongs to it: Marketplace submissions again require at least ten installed active workspaces, held throughout the review, after a period at a lower temporary threshold. The CLI has shipped three times since late July.

Read the full Slack trajectory →

Maddy vs Slack: editorial side-by-side

M
Maddy
COMMS
0.0

A one-binary mail server learning to behave like production infrastructure.

◆ Current state

maddy is an all-in-one SMTP and IMAP server written in Go, aimed at people who want a working mail host without assembling Postfix, Dovecot and a policy daemon themselves. The 0.9 line moved quickly — 0.9.0 through 0.9.5 between late March and late May — with the sequence following a recognisable shape: a feature release, an immediate patch for a broken integration, a security release, then cleanup. Configuration is directive-based, and much of the changelog concerns the behaviour of individual modules like auth.ldap, check.rspamd and check.dnsbl.

◆ Where it's heading

The project is systematically removing the compromises that made early versions convenient. Obsolete SASL LOGIN was disabled by default, the STARTTLS plaintext fallback was dropped, the maddyctl symlink behaviour and the implicit run command were deleted after four years of deprecation warnings, and libdns providers that have not kept up with 1.x are being cut. Running the other way is operational maturity: no-downtime config reload, queue-length metrics, OpenMetrics fixes, systemd readiness reporting, and SLSA build attestations on release artifacts. This is a project moving from hobbyist-friendly to operator-friendly, and accepting breakage to get there.

◆ Prediction

0.10.0 is already scoped by the deprecations announced in 0.9.1 — expect the flagged libdns providers to be removed and gandi to require Bearer tokens. Given the 0.9.x pattern, a feature release followed quickly by an integration fix is the likely shape.

Slack logo
Slack
COMMSCOLLAB
6.3

Slack raises the Marketplace bar back to ten installs while the agent platform consolidates.

◆ Current state

Slack's developer platform runs two tracks. The agent build-out has produced a spark roughly every two weeks since June — MCP client, a skills plugin targeting Claude Code and Cursor, and Slack Code — and now has a consolidation date attached: assistant_view is deprecated in February 2027, replaced by an Agent Sessions API. The second track is platform administration and tooling, and this window belongs to it: Marketplace submissions again require at least ten installed active workspaces, held throughout the review, after a period at a lower temporary threshold. The CLI has shipped three times since late July.

◆ Where it's heading

The install requirement moving back up is a distribution decision arriving in the middle of a platform push, and the two point the same way. Slack is making it easier to build agents and harder to list one, which favours developers who already have distribution — existing workspace tools and vendors — over a new app hoping the Marketplace supplies its first users. Combined with the assistant deprecation and the Agent Sessions API, the platform is narrowing on one agent surface and one class of builder rather than widening the funnel.

◆ Prediction

The threshold is described as a return from a temporary lower bar rather than a new policy, so the open question is what replaces the Marketplace as the discovery path for an app that cannot reach ten workspaces on its own. These entries do not answer it.

Alternatives to Maddy and Slack

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 Maddy or Slack.

See all Maddy alternatives → · See all Slack alternatives →

Recent activity from Maddy and Slack

Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.

  1. 14d agoSlackUpdated installation requirement for Slack Marketplace apps
  2. 15d agoSlackCLI adds app-approval status checks and custom app icons
  3. 26d agoSlackAnnouncing Slack Code
  4. 26d agoSlackAgent Sessions API replaces assistant_view, deprecated Feb 2027
  5. 1mo agoSlackAnnouncing the Slack MCP and Skills Plugin
  6. 1mo agoSlackCLI adds manifest diff and a Block Kit preview command
  7. 3mo agoMaddymaddy 0.9.5 fixes nested pipeline logging and systemd reload reporting
  8. 4mo agoMaddymaddy 0.9.4 removes the maddyctl symlink and implicit run command
  9. 5mo agoMaddymaddy 0.9.3 patches an LDAP injection flaw in auth.ldap
  10. 5mo agoMaddymaddy 0.9.2 fixes an rspamd panic on unspecified tls_client
  11. 5mo agoMaddymaddy 0.9.1 flags libdns providers for removal in 0.10.0
  12. 5mo agoMaddymaddy 0.9.0 adds no-downtime configuration reloading

Frequently asked questions

What is the difference between Maddy and Slack?

They serve adjacent needs but don't currently overlap on shipped themes. Slack is currently shipping more aggressively (velocity 6.3 vs 0.0), with 1 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 Maddy better than Slack?

Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Slack is currently shipping more aggressively (velocity 6.3 vs 0.0), with 1 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 Maddy?

Top Maddy alternatives in Comms are ranked by recent ship velocity. Browse the "Maddy alternatives" section above for the current picks, or visit /alternatives/maddy for the full list with editorial commentary on each.

What are the best alternatives to Slack?

Top Slack alternatives in Comms are ranked by recent ship velocity. Browse the "Slack alternatives" section above for the current picks, or visit /alternatives/slack for the full list with editorial commentary on each.