Who this comparison is for
MailBridge highlights
- IMAP/SMTP account sync (OAuth/user-pass) + inbox views
- HMAC-secured Bridge API with IP allowlists & rotation
Twilio SendGrid highlights
- Proven deliverability & scalable send APIs
- Event webhooks and templates for transactional sends
Capability matrix
| Capability | MailBridge | Twilio SendGrid | Notes |
|---|---|---|---|
| IMAP inbox sync (headers, bodies, attachments) | Full | None | MailBridge poller vs send-only API |
| SMTP direct send via connected accounts | Full | None | SendGrid uses proprietary API rather than SMTP relay for most plans |
| Programmatic send API | Full | Full | Bridge API (HMAC) vs SendGrid REST |
| Drafts & templates workflow | Full | Partial | Send-side templates only; no IMAP-backed drafts |
| Bulk sender (queued campaigns) | Full | Partial | MailBridge queued SMTP; SendGrid has Marketing Campaigns (separate feature set) |
| Inbound events → workspace log | Native | via_webhook | MailBridge logs inbound mail; SendGrid posts events/webhooks |
| Bounce/DSN handling to events bus | Full | Full | Both emit bounce events; mechanisms differ |
| Verification cache (MX/SMTP/domain) | Full | Partial | MailBridge probes & caches; SendGrid validates sender domains for API send |
| HMAC Bridge (timestamped, replay window, keys) | Native | None | SendGrid keys are static API tokens |
| OAuth providers (Google/365) for inbox | Full | None | MailBridge connects mailboxes; SendGrid is not an inbox client |
| Event bus (Email.received/sent/bounced) | Native | via_webhook | MailBridge publishes workspace events |
| .eml import/preview | Full | None | — |
- This comparison focuses on inbox sync + programmatic send + operational controls. Marketing suite features are out of scope.
- Tokens in the matrix (full/partial/none/native/via_webhook/manual) provide quick capability shorthand.
Total cost of ownership
MailBridge can lower total ops cost where unified inbox + programmatic send + logging are required. SendGrid remains ideal for high-scale transactional send where an inbox is not needed.
Assumptions
- 3–10 connected inboxes, mixed inbound/outbound
- Apps posting via HMAC Bridge, internal audit required
Migration plan
From SendGrid · Map API senders → connect inboxes → cut over Bridge calls
-
1
Create sending identities in MailBridge (connect IMAP/SMTP or OAuth)
-
2
Mint HMAC bridge keys, set IP allowlist, rotate secrets
-
3
Switch app calls from SendGrid REST to /bridge/{clientId}/compose.send
-
4
Enable bounce listeners and verify event parity
Security
- AES-256 at rest; TLS 1.2+ in transit
- HMAC-SHA256 signatures with replay window
- KeyVault-managed secrets & rotation
Evidence & sources
| Claim | Value | Source |
|---|---|---|
| Bridge API HMAC headers | X-EH-TS / X-EH-SIG |
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Timestamped, rotating keys
|
| Inbox sync cadence | IMAP poll ~1 min |
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Guarded poller
|
About MailBridge
MailBridge centralizes business email inside your Velaxe workspace. Connect IMAP/SMTP accounts (including OAuth providers) and the background poller ingests folders, flags, bodies, and attachments with safe throttles. Compose drafts with uploads, send immediately, or enqueue to the bulk sender with pacing and retry policies.
A hardened, timestamped HMAC bridge lets external apps request account suggestions or send mail via signed requests—no CORS headaches. Connections include scopes, IP allowlists, and rotating secrets with audit logs and analytics.
Verification tools probe domains/MX/SMTP and cache outcomes to reduce bounces. Events integrate with workflows and AI responses so teams can automate follow-ups and logging into CRM/Chronicle.