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Comparison · Comms

Mailu vs Respond.io

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

Mailu vs Respond.io: at a glance

FeatureMailuRespond.io
SectorCommsComms, Support
Velocity score5.07.5
Sparks · 30d02
Top themesmaintenance-branch, roundcube, cve-patching, self-hosted-mailomnichannel-inbox, ai-agents, usage-based-billing, integrations
Last editorial update5d ago4d ago
WebsiteVisit →

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.

Read the full Mailu trajectory →

What is Respond.io?

respond.io is layering an agent-authoring copilot and consumption billing on top of its omnichannel inbox.

respond.io ships something visible every few days across three fronts: channel coverage, the agent-facing inbox, and AI. Microsoft 365 and Outlook joined as a full email channel with workflow routing and reports, Calendly arrived as an integration, and Instagram Story mentions can now open conversations automatically. The inbox itself picked up a Cmd+K command palette, drag-out full-size image saving, and browser-tab unread signalling, while the mobile app gained offline message queuing.

Read the full Respond.io trajectory →

Mailu vs Respond.io: editorial side-by-side

M
Mailu
COMMS
5.0

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.

R
Respond.io
COMMSSUPPORT
7.5

respond.io is layering an agent-authoring copilot and consumption billing on top of its omnichannel inbox.

◆ Current state

respond.io ships something visible every few days across three fronts: channel coverage, the agent-facing inbox, and AI. Microsoft 365 and Outlook joined as a full email channel with workflow routing and reports, Calendly arrived as an integration, and Instagram Story mentions can now open conversations automatically. The inbox itself picked up a Cmd+K command palette, drag-out full-size image saving, and browser-tab unread signalling, while the mobile app gained offline message queuing.

◆ Where it's heading

Two moves stand out from the steady feature drip. Copilot went into every workspace as an agent builder that drafts an AI Agent from a description and runs test cases against it before publishing — respond.io is attacking the authoring problem, not the runtime one. Alongside it, AI Credit On-Demand converts the AI allowance from a hard cap into metered overage, so automation stops breaking mid-conversation and AI becomes consumption revenue. The remaining work is a methodical widening of channels and the surfaces an agent touches all day.

◆ Prediction

Expect more channels to arrive in the same shape Outlook did — inbox, workflows, and reports together — and Copilot's authoring surface to extend past agents into workflows. The AI Agent wait-time and Copilot test-case work both point toward more pre-publish validation tooling.

Alternatives to Mailu and Respond.io

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 Respond.io.

See all Mailu alternatives → · See all Respond.io alternatives →

Recent activity from Mailu and Respond.io

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

  1. 5d agoRespond.ioBrowser tabs show unread counts and assignment status
  2. 6d agoRespond.ioMicrosoft 365 and Outlook arrive as an email channel
  3. 6d agoMailuRoundcube 1.6.18 bump clears a TLS-config warning
  4. 7d agoRespond.ioMobile app queues messages sent offline
  5. 9d agoRespond.ioDrag full-size images from the Inbox; custom export ranges
  6. 14d agoRespond.ioAI Credit On-Demand bills overage instead of stopping AI
  7. 14d agoRespond.ioCopilot lands in every workspace with an AI Agent Builder
  8. 23d agoMailuAutoconfig fix for modern K-9 Mail
  9. 25d agoMailuRoundcube 1.6.17 closes two CVEs
  10. 1mo agoMailuSets X-Forwarded-By in response to a GHSA advisory
  11. 1mo agoMailuAdmin UI keeps form values on failed submit
  12. 1mo agoMailuEscapes sieve fields, fixing autoreplies with special characters

Frequently asked questions

What is the difference between Mailu and Respond.io?

They serve adjacent needs but don't currently overlap on shipped themes. Respond.io is currently shipping more aggressively (velocity 7.5 vs 5.0), with 2 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 Respond.io?

Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Respond.io is currently shipping more aggressively (velocity 7.5 vs 5.0), with 2 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 Respond.io?

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