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Comparison · Comms
Rspamd vs Synapse
A side-by-side editorial comparison of Rspamd and Synapse — release velocity, themes, recent moves, and the top alternatives to consider.
Rspamd vs Synapse: at a glance
What is Rspamd?
Rspamd 4.2 hardens its parsers and ships memory-safety fixes three releases running.
The 4.2 line opened in September with a public suffix lookup replacing the old TLD tables, attachment content extraction for SVG, OOXML and DOCX, and one scheduler over the symbol dependency graph. 4.2.1 fixed critical memory-safety bugs including an HTTP heap overflow. 4.2.2 added wallet-address detection across twelve named currencies and changed MIME digests. 4.2.3 stopped trusting ARC forwarders whose seal fails and merged duplicate RBL queries, so a rule scores once per matched value.
What is Synapse?
Synapse opens the 1.165 cycle on schedule after two 1.164 patches
Synapse keeps its two-to-three-week cycle of candidates and stables. 1.164.0 went stable on 27 October with support for Matrix v1.16 and v1.17 and a dedicated endpoint for delayed events, followed by 1.164.1 and 1.164.2 patches. 1.165.0rc1 arrived on 4 November with only a changelog link, so its contents are not visible here.
Rspamd vs Synapse: editorial side-by-side
Rspamd
5.0COMMS
Rspamd 4.2 hardens its parsers and ships memory-safety fixes three releases running.
◆ Current state
The 4.2 line opened in September with a public suffix lookup replacing the old TLD tables, attachment content extraction for SVG, OOXML and DOCX, and one scheduler over the symbol dependency graph. 4.2.1 fixed critical memory-safety bugs including an HTTP heap overflow. 4.2.2 added wallet-address detection across twelve named currencies and changed MIME digests. 4.2.3 stopped trusting ARC forwarders whose seal fails and merged duplicate RBL queries, so a rule scores once per matched value.
◆ Where it's heading
The input-hardening walk from 4.1.x has become line-wide policy: limits on untrusted UCL, bounded PDF and decompression work, and HTML parsing that matches browsers so content cannot hide from the scan. Detection moves the same way, into what attachments and hidden text actually contain. Point releases keep carrying incompatible changes to digests and scoring, so operators need to read the notes on every update.
◆ Prediction
Expect more browser-parity fixes in HTML and URL handling, and attachment extraction beyond the SVG and OOXML set. The planned flip of allow_file_and_shm_inputs to false does not appear in the 4.2 notes, so it remains the breaking change to watch.
Synapse
5.0COMMS
Synapse opens the 1.165 cycle on schedule after two 1.164 patches
◆ Current state
Synapse keeps its two-to-three-week cycle of candidates and stables. 1.164.0 went stable on 27 October with support for Matrix v1.16 and v1.17 and a dedicated endpoint for delayed events, followed by 1.164.1 and 1.164.2 patches. 1.165.0rc1 arrived on 4 November with only a changelog link, so its contents are not visible here.
◆ Where it's heading
The cadence is steady: a candidate roughly a week after each stable, then stable about a week later. Much of the recent work has been security dependency bumps, including the eMudhra CA distrust, Pillow 13 and msgpack, alongside spec-version support.
◆ Prediction
1.165.0 stable is likely within about a week, but the entries do not say what it contains.
Alternatives to Rspamd and Synapse
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 Rspamd or Synapse.
Netcore Cloud
Netcore's blog keeps pitching search-plus-email on one data core, with no product release.
Superhuman
Superhuman gives team admins a console and Enterprise a usage report that counts MCP.
Slack
Slack's CLI now points coding agents to its MCP server and Skills plugin
Whereby
Whereby folds three months into one digest and still lists nothing specific
Rocket.Chat
Rocket.Chat's fifth 9.0 candidate is about load: notifications, presence and startup.
See all Rspamd alternatives → · See all Synapse alternatives →
Recent activity from Rspamd and Synapse
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 16h agoSynapseSynapse 1.165.0rc1 opens the next release cycle
- 2d agoSynapseSynapse 1.164.2 patch release
- 7d agoSynapseSynapse 1.164.1: msgpack memory-exhaustion fix, status clearing
- 8d agoSynapseSynapse 1.164.0: Matrix v1.16/v1.17 support goes stable
- 12d agoSynapseSynapse 1.164.0rc3: Pillow 13 security bump
- 12d agoSynapseSynapse 1.163.2: Pillow critical security backport
- 15d agoRspamd4.2.3: ARC trust fix, merged RBL queries, browser-style HTML parsing
- 25d agoRspamd4.2.2: crypto wallet detection and changed MIME digests
- 1mo agoRspamd4.2.1: critical HTTP and memory-safety fixes
- 1mo agoRspamd4.2.0: public suffix lookup and attachment content extraction
- 2mo agoRspamdCloses an arbitrary file read reachable by any TCP client
- 3mo agoRspamdController accepted any password on a malformed hash
Frequently asked questions
What is the difference between Rspamd and Synapse?
They serve adjacent needs but don't currently overlap on shipped themes. Rspamd and Synapse are shipping at a similar cadence (velocity 5.0 vs 5.0, both within Sparkpulse's "active" band). See the at-a-glance table above for a side-by-side breakdown of velocity, recent sparks, and editorial themes.
Is Rspamd better than Synapse?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Rspamd and Synapse are shipping at a similar cadence (velocity 5.0 vs 5.0, both within Sparkpulse's "active" band). For your specific use case, the alternatives sections above list other Comms products to evaluate alongside.
What are the best alternatives to Rspamd?
Top Rspamd alternatives in Comms are ranked by recent ship velocity. Browse the "Rspamd alternatives" section above for the current picks, or visit /alternatives/rspamd for the full list with editorial commentary on each.
What are the best alternatives to Synapse?
Top Synapse alternatives in Comms are ranked by recent ship velocity. Browse the "Synapse alternatives" section above for the current picks, or visit /alternatives/synapse for the full list with editorial commentary on each.