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Comparison · Comms
Gromox vs Stalwart
A side-by-side editorial comparison of Gromox and Stalwart — release velocity, themes, recent moves, and the top alternatives to consider.
Gromox vs Stalwart: at a glance
What is Gromox?
Gromox keeps closing the gap with Exchange one protocol surface at a time — this round it's IMAP flags and Outlook for Mac.
Gromox ships a numbered release roughly monthly, each a mix of Exchange-protocol enhancements and fixes across emsmdb, EWS, IMAP, and the store layer. Version 3.10 makes midb synchronize IMAP message flags to and from the mailbox so they survive deletion of midb.sqlite3, adds IMAP keyword support, teaches EWS the Outlook-for-Mac smart response draft types, extends FindPeople and GetUserPhoto to personal contacts, and adds a short-TTL cache for recurring user ID and group membership lookups.
What is Stalwart?
Stalwart adds full SCIM v2 provisioning and 24-language calendar support as its standards coverage extends further than most commercial mail servers.
Stalwart is maintaining a weekly-or-faster release cadence, with alternating feature releases and dense bug-fix releases. The v0.16.20 release landed full SCIM v2 (Enterprise) including cursor-based pagination and the IPSIE lifecycle profile, conference links in calendar invites, and 24 new calendar interface translations. Below the feature line, the project is steadily closing correctness gaps across JMAP, CalDAV, IMAP, and MTA — many of them edge-case RFC compliance issues.
Gromox vs Stalwart: editorial side-by-side
Gromox
2.5COMMS
Gromox keeps closing the gap with Exchange one protocol surface at a time — this round it's IMAP flags and Outlook for Mac.
◆ Current state
Gromox ships a numbered release roughly monthly, each a mix of Exchange-protocol enhancements and fixes across emsmdb, EWS, IMAP, and the store layer. Version 3.10 makes midb synchronize IMAP message flags to and from the mailbox so they survive deletion of midb.sqlite3, adds IMAP keyword support, teaches EWS the Outlook-for-Mac smart response draft types, extends FindPeople and GetUserPhoto to personal contacts, and adds a short-TTL cache for recurring user ID and group membership lookups.
◆ Where it's heading
The project is methodically completing Microsoft's protocol surface rather than building an alternative one. EWS went from partial handlers in 3.2 to the full meeting, delegate, and task surface in 3.6, and now picks up client-specific dialects like Outlook for Mac's draft types. IMAP is on the same path — keywords and colour categories in 3.8, IMAP4rev2 pieces, and now flag durability. Meanwhile the store layer keeps being split and cached for operability. The audience is clearly administrators migrating off Exchange or Kopano who need existing clients to behave unchanged.
◆ Prediction
Expect IMAP4rev2 coverage to keep filling in and more client-specific EWS dialects to appear as particular Outlook builds are tested against it.
Stalwart
6.3COMMS
Stalwart adds full SCIM v2 provisioning and 24-language calendar support as its standards coverage extends further than most commercial mail servers.
◆ Current state
Stalwart is maintaining a weekly-or-faster release cadence, with alternating feature releases and dense bug-fix releases. The v0.16.20 release landed full SCIM v2 (Enterprise) including cursor-based pagination and the IPSIE lifecycle profile, conference links in calendar invites, and 24 new calendar interface translations. Below the feature line, the project is steadily closing correctness gaps across JMAP, CalDAV, IMAP, and MTA — many of them edge-case RFC compliance issues.
◆ Where it's heading
Stalwart is building toward parity with commercial enterprise mail servers on identity federation and provisioning (SCIM v2, VAPID for web push, DMARCbis/DKIM2 already landed). The pace of RFC implementation is unusually aggressive for an open-source project; the combination of JMAP, CalDAV, IMAP UIDONLY/UIDBATCHES, and SCIM v2 positions it as a viable self-hosted alternative for organizations that need standards compliance without vendor lock-in.
◆ Prediction
WebAuthn/passkey-based authentication and improved multi-tenant administration tooling are the most likely next capability additions, given the current trajectory toward enterprise identity management.
Alternatives to Gromox and Stalwart
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 Gromox or Stalwart.
Superhuman
Superhuman rebuilt its mobile apps and wired every inbox into AI assistants — the email client is becoming a suite.
Chatwoot
Chatwoot is building an AI-first support platform, with Captain gaining audience targeting and macro automation reaching the keyboard-native workflow.
Signal Desktop
Signal adds granular notification controls: badge content, muted threads, restore defaults
Zoho Cliq
Zoho Cliq 7.0 bets on AI conversation summaries and Neat hardware to close the gap with enterprise messaging platforms
Krisp
Krisp adds deepfake detection and expands Voice Translation as its Call Center AI platform deepens enterprise compliance tools.
See all Gromox alternatives → · See all Stalwart alternatives →
Recent activity from Gromox and Stalwart
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 10d agoStalwartv0.16.21
- 17d agoStalwartv0.16.20 ⚡
- 23d agoStalwartv0.16.19
- 25d agoGromox3.10 makes IMAP flags durable and teaches EWS Outlook for Mac's drafts
- 1mo agoStalwartv0.16.18
- 1mo agoStalwartv0.16.17
- 1mo agoStalwartv0.16.16
- 1mo agoGromox3.9 makes room bookings and EWS meetings properly actionable
- 2mo agoGromox3.8 splits the Information Store per store and extends IMAP
- 4mo agoGromox3.7 fixes shared calendars, EWS fields and Thunderbird discovery
- 5mo agoGromox3.6 lands the full EWS meeting, delegate and task surface ⚡
- 6mo agoGromox3.5 adds per-service listen directives and fixes notifications
Frequently asked questions
What is the difference between Gromox and Stalwart?
They serve adjacent needs but don't currently overlap on shipped themes. Stalwart 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 Gromox better than Stalwart?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Stalwart 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 Gromox?
Top Gromox alternatives in Comms are ranked by recent ship velocity. Browse the "Gromox alternatives" section above for the current picks, or visit /alternatives/gromox for the full list with editorial commentary on each.
What are the best alternatives to Stalwart?
Top Stalwart alternatives in Comms are ranked by recent ship velocity. Browse the "Stalwart alternatives" section above for the current picks, or visit /alternatives/stalwart for the full list with editorial commentary on each.