Zoho Cliq
Zoho Cliq 7.0 bets on AI conversation summaries and Neat hardware to close the gap with enterprise messaging platforms
Comparison · Comms
Mailu vs Slack
A side-by-side editorial comparison of Mailu and Slack — release velocity, themes, recent moves, and the top alternatives to consider.
Mailu vs Slack: at a glance
What is Mailu?
Mailu ships one pinned release per issue, and most of them are Roundcube's.
The 2024.06 branch releases on demand: an issue or PR comes in, a pinned version goes out, and the changelog is one or two lines. Four of the six most recent releases are webmail-driven — three Roundcube bumps in this window alone, the latest to 1.6.18 clearing a TLS-configuration warning, an earlier one to 1.6.17 closing two CVEs. The remainder are Mailu's own code: an X-Forwarded-By header fix tied to a published advisory, sieve field escaping that repaired autoreplies and closed an injection path, and two admin-UI form flow corrections.
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.
Mailu vs Slack: editorial side-by-side
Mailu
5.0COMMS
Mailu ships one pinned release per issue, and most of them are Roundcube's.
◆ Current state
The 2024.06 branch releases on demand: an issue or PR comes in, a pinned version goes out, and the changelog is one or two lines. Four of the six most recent releases are webmail-driven — three Roundcube bumps in this window alone, the latest to 1.6.18 clearing a TLS-configuration warning, an earlier one to 1.6.17 closing two CVEs. The remainder are Mailu's own code: an X-Forwarded-By header fix tied to a published advisory, sieve field escaping that repaired autoreplies and closed an injection path, and two admin-UI form flow corrections.
◆ Where it's heading
This is a maintenance branch behaving exactly as a maintenance branch should, and the pinned-version model is the product: operators get upstream security work packaged and tagged without tracking Roundcube themselves. The security items divide cleanly — most arrive from bundled components, a minority from Mailu's own code, and the project patches both on the same cadence. Nothing in this window suggests new capability is being developed on this branch.
◆ Prediction
Expect the next release to follow the same trigger: a Roundcube advisory or a client compatibility report producing a single-line changelog and a new pinned tag. Any feature work would be happening on the main version, which this feed does not cover.
Slack
6.3COMMSCOLLAB
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 Mailu 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 Mailu or Slack.
Krisp
Krisp adds deepfake detection and expands Voice Translation as its Call Center AI platform deepens enterprise compliance tools.
Netcore Cloud
Netcore's recent entries are blog content, not product releases — the signal is a BFSI and ecommerce vertical sales push.
Canary Mail
Canary Mail ships AI chat history while sustaining a cross-platform bug fix cadence.
Superhuman
Superhuman is becoming the email layer for AI agents, not just the fastest email client.
Salesmsg
Salesmsg now runs the entire sales-to-NPS loop in one thread — outbound, AI reply, booking, survey, and routing.
Recent activity from Mailu and Slack
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 13d agoSlackUpdated installation requirement for Slack Marketplace apps
- 14d agoSlackCLI adds app-approval status checks and custom app icons
- 25d agoSlackAnnouncing Slack Code ⚡
- 25d agoSlackAgent Sessions API replaces assistant_view, deprecated Feb 2027
- 1mo agoMailuRoundcube 1.6.18 bump clears a TLS-config warning
- 1mo agoSlackAnnouncing the Slack MCP and Skills Plugin ⚡
- 1mo agoSlackCLI adds manifest diff and a Block Kit preview command
- 1mo agoMailuAutoconfig fix for modern K-9 Mail
- 1mo agoMailuRoundcube 1.6.17 closes two CVEs
- 1mo agoMailuSets X-Forwarded-By in response to a GHSA advisory
- 2mo agoMailuAdmin UI keeps form values on failed submit
- 2mo agoMailuEscapes sieve fields, fixing autoreplies with special characters
Frequently asked questions
What is the difference between Mailu and Slack?
They serve adjacent needs but don't currently overlap on shipped themes. Slack is currently shipping more aggressively (velocity 6.3 vs 5.0), 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 Mailu 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 5.0), 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 Mailu?
Top Mailu alternatives in Comms are ranked by recent ship velocity. Browse the "Mailu alternatives" section above for the current picks, or visit /alternatives/mailu 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.