Rspamd
Rspamd 4.3 fixes SPF evaluation order and rejects weak DKIM keys, with results that change.
Comparison · Comms
Dovecot vs Slack
A side-by-side editorial comparison of Dovecot and Slack — release velocity, themes, recent moves, and the top alternatives to consider.
Dovecot vs Slack: at a glance
What is Dovecot?
Dovecot's 2.4 branch is being hardened release by release after a breaking rewrite.
Dovecot is the IMAP and POP3 server behind a large share of the world's mailboxes. The 2.4 branch opened in January 2025 with a deliberately incompatible release — configuration files must be rewritten, the plugin section is gone, and several long-standing features were removed outright — and every release since has been consolidation on top of it. The pattern is consistent: each point release leads with critical CVE fixes, then lists incremental changes. The latest, 2.4.5, carries twelve CVEs alongside post-quantum ML-KEM support, full-text phrase searching and a throttling response code.
What is Slack?
Slack now hosts any A2A agent without Slack-specific code.
Slack's developer channel is almost all agent plumbing. On 10 November Slack became an A2A (Agent2Agent) client: a team hosts its own agent, publishes an Agent Card, and Slack calls it when people talk to it, with no request URL, event handling or Slack-specific logic. This follows Slackbot skills managed through Web API methods, a Slack CLI that points coding agents to the Slack MCP server, and a new requirement that Work Objects embeds allow the slack-mcps.com frame ancestor.
Dovecot vs Slack: editorial side-by-side
Dovecot
2.5COMMS
Dovecot's 2.4 branch is being hardened release by release after a breaking rewrite.
◆ Current state
Dovecot is the IMAP and POP3 server behind a large share of the world's mailboxes. The 2.4 branch opened in January 2025 with a deliberately incompatible release — configuration files must be rewritten, the plugin section is gone, and several long-standing features were removed outright — and every release since has been consolidation on top of it. The pattern is consistent: each point release leads with critical CVE fixes, then lists incremental changes. The latest, 2.4.5, carries twelve CVEs alongside post-quantum ML-KEM support, full-text phrase searching and a throttling response code.
◆ Where it's heading
Two things are being worked at once. Security is the visible half, and the volume is striking — resource-exhaustion and parser issues in IMAP THREAD, LIST and ID, a CRIME-style compression side channel, an authentication bypass through XCLIENT forwarding. The quieter half is that fixes are increasingly gated behind version declarations: the THREAD fix needs a new index format enabled only by raising dovecot_storage_version. That mechanism, introduced with 2.4.0, is now doing real work, letting operators take format changes on their own schedule.
◆ Prediction
Experimental flags for mail UTF-8 and IMAP4rev2 have carried unchanged through every 2.4 release so far; the next branch-defining move is one of those graduating to default rather than another security round.
Slack
6.3COMMSCOLLAB
Slack now hosts any A2A agent without Slack-specific code.
◆ Current state
Slack's developer channel is almost all agent plumbing. On 10 November Slack became an A2A (Agent2Agent) client: a team hosts its own agent, publishes an Agent Card, and Slack calls it when people talk to it, with no request URL, event handling or Slack-specific logic. This follows Slackbot skills managed through Web API methods, a Slack CLI that points coding agents to the Slack MCP server, and a new requirement that Work Objects embeds allow the slack-mcps.com frame ancestor.
◆ Where it's heading
Slack is lowering the cost of putting outside agents in front of its users: first skills as code, then MCP pointers for coding agents, now a standard protocol in place of the Slack app model for agents. The platform is positioning itself as the place where agents built anywhere meet the people who use them.
◆ Prediction
Expect more A2A follow-ups, such as agents appearing in Slackbot or skills surfaces and richer Agent Card features, given how fast the agent releases have stacked up since October.
Alternatives to Dovecot 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 Dovecot or Slack.
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 Dovecot alternatives → · See all Slack alternatives →
Recent activity from Dovecot and Slack
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 4d agoSlackBring your A2A agents to Slack ⚡
- 8d agoSlackWork Objects embeds require the slack-mcps.com frame ancestor
- 10d agoSlackSlack CLI 4.13 tells coding agents about Slack MCP and Skills
- 10d agoSlackSlack Skills Plugin installs in Claude Code from its own marketplace
- 12d agoSlackUpdated low-usage submission criteria for Slack Marketplace apps
- 15d agoSlackSlack CLI 4.12.0, the fourth CLI release in October
- 2mo agoDovecotTwelve CVEs fixed; ML-KEM and full-text phrase search arrive
- 6mo agoDovecotCVE fixes in variable expansion and CRAM-SHA authentication
- 7mo agoDovecotCVE fixes for base64 auth DoS and decode2text
- 1y agoDovecotAuth cache key collision fixed; libpcre2 becomes a dependency
- 1y agoDovecot2.4 branch signing key rotates; packages break 2.3 configs
- 1y agoDovecotDovecot 2.4 lands: configs must be rewritten, director removed ⚡
Frequently asked questions
What is the difference between Dovecot and Slack?
They serve adjacent needs but don't currently overlap on shipped themes. Slack is currently shipping more aggressively (velocity 6.3 vs 2.5), 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 Dovecot 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 2.5), 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 Dovecot?
Top Dovecot alternatives in Comms are ranked by recent ship velocity. Browse the "Dovecot alternatives" section above for the current picks, or visit /alternatives/dovecot 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.