Postmark
Postmark adds its own SOC 2 Type 2 report to a run of security work.
Comparison · Comms
Gromox vs Proton Bridge
A side-by-side editorial comparison of Gromox and Proton Bridge — release velocity, themes, recent moves, and the top alternatives to consider.
Shared themes:imap
Gromox vs Proton Bridge: at a glance
What is Gromox?
Gromox 3.13 adds scripts to move Exchange-for-All systems onto it.
Gromox ships a numbered release roughly monthly. 3.13 adds scripts to convert E4A systems to Gromox, full two-way sync of IMAP keywords with MAPI categories, multi-message vCard export and audit logging in emsmdb and zcore, and fixes an EWS gap where any user could answer, alter or move meeting requests in other mailboxes. 3.12 moved MAPI-to-internet conversion onto VMIME with RFC 2231 filenames; 3.11 added IMAP FETCH BINARY and Sent Items copies for send-as and send-on-behalf on shared mailboxes.
What is Proton Bridge?
Proton Bridge v3.27.2 adds support for the oo7 keyring on Linux.
Proton Bridge's releases in 2026 have been almost entirely maintenance: monthly vulnerability patches, Go toolchain bumps, IMAP RFC-compliance fixes and recovery from corrupted sync state files. v3.27.2 adds one item, support for the oo7 keyring service, a Rust-based Secret Service implementation used on newer Linux desktops.
Gromox vs Proton Bridge: editorial side-by-side
Gromox
2.5COMMS
Gromox 3.13 adds scripts to move Exchange-for-All systems onto it.
◆ Current state
Gromox ships a numbered release roughly monthly. 3.13 adds scripts to convert E4A systems to Gromox, full two-way sync of IMAP keywords with MAPI categories, multi-message vCard export and audit logging in emsmdb and zcore, and fixes an EWS gap where any user could answer, alter or move meeting requests in other mailboxes. 3.12 moved MAPI-to-internet conversion onto VMIME with RFC 2231 filenames; 3.11 added IMAP FETCH BINARY and Sent Items copies for send-as and send-on-behalf on shared mailboxes.
◆ Where it's heading
The project keeps completing Exchange behaviour for clients that expect it, now including shared-mailbox Sent Items and meeting handling that matches Exchange. 3.13's conversion scripts and audit logging point at migration and compliance as the adoption path, alongside the IMAP work that has run since 3.8. Permission checks on EWS calendar operations show the protocol surface now gets security review, not only coverage.
◆ Prediction
Expect more EWS permission and behaviour corrections and continued IMAP4rev2 coverage; the E4A scripts suggest further migration tooling from other groupware.
Proton Bridge
2.5COMMS
Proton Bridge v3.27.2 adds support for the oo7 keyring on Linux.
◆ Current state
Proton Bridge's releases in 2026 have been almost entirely maintenance: monthly vulnerability patches, Go toolchain bumps, IMAP RFC-compliance fixes and recovery from corrupted sync state files. v3.27.2 adds one item, support for the oo7 keyring service, a Rust-based Secret Service implementation used on newer Linux desktops.
◆ Where it's heading
Bridge remains a stable compatibility layer rather than a growing product. The small additions that do land are about running cleanly on more desktop environments.
◆ Prediction
Expect the next monthly security patch release; the entries show no sign of feature work.
Alternatives to Gromox and Proton Bridge
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 Proton Bridge.
Element X Android
Element X Android turns on multi-select forwarding and better search in v26.11.0.
Fonoster
Fonoster lets voice agents pick Anthropic, Google or Groq models and record calls with one switch.
Salesmsg
Salesmsg's Sherpa AI now sends replies and builds broadcasts on request, with approval first.
Netcore Cloud
Netcore keeps publishing unified-platform explainers with no product release.
Element
Element 1.12.34 RC.1 keeps call picture-in-picture and adds read receipts to the labs timeline.
See all Gromox alternatives → · See all Proton Bridge alternatives →
Recent activity from Gromox and Proton Bridge
Latest ship moves from both products, interleaved chronologically. ⚡ = editorial spark.
- 3d agoProton Bridgev3.27.2: support for the oo7 keyring service
- 11d agoGromoxGromox 3.13
- 1mo agoGromoxGromox 3.12
- 1mo agoProton Bridgev3.27.1: recover from corrupted sync state
- 1mo agoGromoxGromox 3.11
- 2mo agoProton Bridgev3.27.0: August security patches and IMAP fixes
- 2mo agoGromox3.10 makes IMAP flags durable and teaches EWS Outlook for Mac's drafts
- 2mo agoProton Bridgev3.26.0: July security patches and cleanup
- 3mo agoGromox3.9 makes room bookings and EWS meetings properly actionable
- 4mo agoGromox3.8 splits the Information Store per store and extends IMAP
- 5mo agoProton Bridgev3.25.0: clearer errors, legacy updater removed
- 6mo agoProton Bridgev3.24.2: new Go base image
Frequently asked questions
What is the difference between Gromox and Proton Bridge?
Both compete on the same themes — imap — within Comms. Gromox and Proton Bridge are shipping at a similar cadence (velocity 2.5 vs 2.5, 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 Gromox better than Proton Bridge?
Sparkpulse doesn't pick a winner — we score release velocity, not feature parity. Gromox and Proton Bridge are shipping at a similar cadence (velocity 2.5 vs 2.5, 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 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 Proton Bridge?
Top Proton Bridge alternatives in Comms are ranked by recent ship velocity. Browse the "Proton Bridge alternatives" section above for the current picks, or visit /alternatives/proton-bridge for the full list with editorial commentary on each.