Your users’ Gmail, Outlook and IMAP:
one API, every line watched
Sync, search and send from your users' own mailboxes with signed webhooks. Run it on your servers for $708 a year, or let us run it from $24.99 a month.
| Line | Provider | State | Mode | Last event |
|---|---|---|---|---|
| ops@northwind-crm.example | live | push | 2 s ago | |
| dana@harbor-law.example | Microsoft | live | push | 9 s ago |
| intake@kestrel-ats.example | IMAP | syncing | polling | 41 s ago |
| m.okafor@tidewater.example | auth error | push | 3 h ago |
- 14:02:07messageNewops@northwind…200 ✓ 84 ms
- 14:01:58messageMoveddana@harbor…200 ✓ 112 ms
- 14:01:31messageNewintake@kestrel…500 ■ retry 14:02:31
- 14:01:12messageSentops@northwind…200 ✓ 97 ms
Nothing outsourced. Your users' mail is handled only by our code: it never goes to AI APIs, ad networks or analytics tools. Every subprocessor is named on our subprocessors page.
Mailbox sync is months of the wrong work
IMAP edge cases, OAuth refresh tokens, Gmail history, Graph subscriptions that expire, MIME. None of it is your product.
“Our mailbox bill grows with every customer we win.”
Per-mailbox APIs charge for every connected account. Here the Developer tier is free for 3 mailboxes, self-host is $708 a year with unlimited mailboxes, and Cloud extras are $0.99 each.
“IMAP drops at 3 a.m. and nobody knows which mailbox.”
Every mailbox is a line with a state: live, syncing, throttled or auth error. An auth error says why Google or Microsoft rejected it and gives you the reconnect link.
“Google's yearly security assessment surprised us after launch.”
Gmail for external users needs CASA for your own app. We give you the evidence for our part for free, and tell you up front which paths need no assessment at all.
From connect link to signed webhook
Step 1: Create a connect link
One call returns a single-use link, valid for 24 hours. Send it to your user. No IMAP or OAuth code on your side.
curl -X POST https://inboxwire.buffersoltech.com/v1/connect-links \ -H "Authorization: Bearer $INBOXWIRE_KEY" \ -d '{"account":"cust_4821","redirect":"https://app.example/done"}' # 201 { "url": "https://inboxwire.buffersoltech.com/connect/ltk_9f2c…", "expiresIn": 86400 }Step 2: Your user connects a mailbox
They pick Google or Microsoft, or type an address and we detect the provider. Wrong IMAP password? They see it before anything is saved.
Connect your mailbox
Type your email and we pick the right provider.
dana@harbor-law.exampleDetected: Microsoft 365 · next: consent screen
Step 3: A signed webhook fires
Each new message prints on the ticker with its delivery stamp. If your endpoint was down, replay the missed events in one click.
- 14:02:07messageNewops@northwind…200 ✓ 84 ms
- 14:01:58messageMoveddana@harbor…200 ✓ 112 ms
- 14:01:31messageNewintake@kestrel…500 ■ retry 14:02:31
- 14:01:12messageSentops@northwind…200 ✓ 97 ms
What you get on day one
- 14:02:07messageNewops@northwind…200 ✓ 84 ms
- 14:01:58messageMoveddana@harbor…200 ✓ 112 ms
- 14:01:31messageNewintake@kestrel…500 ■ retry 14:02:31
- 14:01:12messageSentops@northwind…200 ✓ 97 ms
Delivery log with one-click replay
Every webhook attempt keeps its request, response and latency. Filter by status and replay one event or a whole time window.
One REST API
Gmail, Microsoft 365 and any IMAP server behind the same endpoints and the same JSON.
Hosted or self-hosted
The same codebase as a Docker image with a licence key, or run by us. Pick per project.
Free CASA Readiness Kit
SAQ mapping for our components, scan configuration and report, deletion evidence and encryption notes. On every plan, including Developer.
One search syntax
from:, to:, subject:, after: and has:attachment become IMAP SEARCH, Gmail q and Graph filters.
Send as the user, threaded
Reply or forward by message id so Gmail shows it in the same thread. Idempotency-Key makes retries safe.
The security assessment, without the surprise
Gmail for external users needs Google’s yearly security assessment (CASA) for your app. We give you the evidence for our part, free, on every plan. Some apps don’t need it at all: send-only, Workspace-internal, or IMAP. We’ll tell you which you are.
See the CASA Readiness Kit- Send-only apps
- gmail.send is a sensitive scope, not restricted. No CASA.
- Workspace internal
- An Internal OAuth app needs no Google verification.
- Testing mode
- Up to 100 test users, no assessment.
- IMAP with app passwords
- No Google OAuth app involved.
Same core features. About half the price.
Annual billing saves 2% to 13% on plans sold both ways.
Developer
Free forever, for a first integration
$0free
No credit card needed.
- 3 mailboxes forever
- All API features
- Self-host or Cloud
- Community support
- No card
Cloud Starter
We host it, for your first customers
$24.99per month
Cancel anytime from your account.
- 25 mailboxes
- Bring your own OAuth clients
- US region
- 30 day webhook delivery log
- 1 environment
Cloud Growth
Most popularWe host it, for a growing customer base
$1,043.88per year
Cancel anytime from your account.
- 100 mailboxes, $0.99 per extra
- 3 environments
- 90 day delivery log
- Priority support, 1 business day
- Remove connect page badge
Self-host
Run it on your servers
$708per year
Cancel anytime from your account.
- Unlimited instances and mailboxes
- Unlimited API calls
- All updates
- Email support, 2 business days
- Price locked 24 months
Compared with the $1,450 a year licence at emailengine.app and Nylas’ published Pro rates, read 3 Nov 2026. Your price is locked for 24 months. Cancel in two clicks.
Built for
Vertical CRMs, shared inbox and helpdesk tools, applicant tracking, AI email agents, regulated workflow software, and email hosts, where mailbox sync is part of your own product.
Not for
Bulk or cold sending, calendar or contacts or EWS, and getting past Google verification on our app. If you need calendar or EWS, choose Nylas.
Questions, answered
Can a small vendor keep up with Gmail and Microsoft changes?
We track Google and Microsoft changelogs weekly, run contract tests against recorded provider responses, and publish a changelog. That is the whole job of this product.
Will you exist in two years?
We can't promise that for anyone. What we do promise: your price is locked for 24 months, and self-hosted licences keep working offline through the end of the term plus a 30 day grace period.
Is self-hosting a way around Google's CASA assessment?
No. CASA applies to your OAuth app, wherever the code runs. Some paths need none: send-only apps, Workspace-internal apps, testing under 100 users, and IMAP with app passwords. The CASA Readiness Kit shows which one you are.
Is this overkill for 5 mailboxes?
The Developer tier is free for 3 mailboxes with every API feature. A Workspace-internal OAuth app needs no Google verification at all.
Why is it cheaper than EmailEngine and Nylas?
One engineer, no sales team, no calendar or contacts product to carry. Compared with the $1,450 a year licence at emailengine.app and Nylas' published Pro rates, read 3 Nov 2026.
Is my users' email safe?
We store metadata only by default. Credentials are envelope encrypted with a per-organization key, no human reads mail, and a deletion API removes an account and revokes its token.
What happens if I exceed my mailbox limit on Cloud?
Nothing breaks. We never disconnect mailboxes for quota. You get an email and an in-app warning at 90 percent, and extra mailboxes are billed at $0.99 each.
Is Inboxwire by BufferSol affiliated with EmailEngine?
No. Inboxwire by BufferSol is not affiliated with Postal Systems OU. We use ImapFlow, Nodemailer and the provider SDKs, and we did not consult EmailEngine source.
Connect a Gmail account and receive a webhook in 5 minutes
Create a key, create a connect link, watch the ticker.
Free Developer tier, no card. Cancel paid plans in two clicks.