Communication · Integration
ZeptoMail
Add ZeptoMail to your product for your customers, and give your AI agents governed access to it.
ZeptoMail is deliberately narrow. Zoho runs it for transactional mail, the receipts, resets and one-time codes a product cannot afford to lose, and states plainly that bulk and promotional sending does not belong on it, which is why a customer's newsletters have to live somewhere else. That narrowness shows up in the credentials: you do not authorise it with an ordinary suite token but with a send mail token generated inside a mail agent, and the mail agent is the unit that separates one application's sending from another, each carrying its own domain, its own token and its own reporting. Templates are addressed by key or by alias, one or the other but never both in the same request, and there is a batch endpoint for putting the same template in front of many recipients at once. What happens afterwards arrives on a webhook: opens, clicks, and bounces split into hard and soft, posted to a URL you protect with your own key. fastn keeps each token per tenant.
In your product
Embedded for your customers. Per-tenant auth, no per-customer code, maintained by fastn.
Give each customer their own mail agent and token, so their transactional mail is sent, tracked and reported entirely apart from anybody else's.
Send from a template by key or alias so your product supplies the data while the customer owns the wording.
Use the batch endpoint when one template goes to many recipients, instead of making a separate call per person.
Consume the bounce webhook and tell hard from soft, because one of them means stop and the other means try again later.
For your AI agents
Governed, audited access for the agents you build, through the MCP server.
An agent traces a missing password reset to the bounce that came back for it.
An agent sends an approved transactional message within scoped permissions, with the mail agent it used recorded.
An agent says plainly that this connection carries transactional mail only, so a marketing send has to go somewhere else.
Example prompt
Did this one-time code reach the recipient, and if it bounced, was the bounce hard or temporary?
Set up ZeptoMail in 4 steps
- 01Enable the ZeptoMail connector in your fastn dashboard.
- 02Have each customer create a mail agent for your product, verify their sending domain, and supply the send mail token it issues.
- 03Map the templates you send by key or alias, point the open, click and bounce webhooks at your endpoint, and protect them with your own key.
- 04Call it from your product and expose the same connection to your agents through the MCP gateway.
Why teams use the ZeptoMail integration
What you get by embedding it with fastn instead of building it yourself.
- Ship a ZeptoMail integration without building it. Your customers connect their own ZeptoMail account inside your product and work their messages, conversations and participants there, with no per-customer code on your side.
- Handle the part that actually costs time: anything sent is user-visible, so duplicates and misfires are immediately embarrassing. fastn owns the auth, token refresh, rate limits, pagination and breaking-change fixes, so a ZeptoMail update is not your on-call problem.
- One integration serves your product and your agents. The same governed ZeptoMail connection powers in-product features and gives AI agents scoped, audited access, so you put the right message in front of the right team automatically without wiring it twice.
Used by these teams
Works well with
SendGrid
Amazon SES
ResendOften used alongside
Tools the same teams tend to run next to ZeptoMail, across other categories.
Aircall
Calendly
Gong
Google CalendarZeptoMail integration FAQ
How do I add a ZeptoMail integration to my product?
Enable the ZeptoMail connector in your fastn dashboard, then let each customer authenticate their own ZeptoMail account. fastn handles the OAuth flow, token storage and refresh per tenant, so there is no ZeptoMail client code in your app and no per-customer branch in your codebase. Setup is 4 steps.
Do my customers each connect their own ZeptoMail account?
Yes. Every connection is scoped to the individual customer, so each authorises their own ZeptoMail account and only ever sees their own messages, conversations and participants. That per-tenant isolation is the point of an embedded integration: you support the long tail of customer setups without maintaining an integration per customer.
Can AI agents use this ZeptoMail integration?
Yes. The same connection is exposed to your agents through the fastn MCP gateway, with permissions scoped per tenant and every call audited. An agent traces a missing password reset to the bounce that came back for it.
Who maintains the ZeptoMail integration?
fastn does. When ZeptoMail changes an endpoint, deprecates a field or alters its auth, the fix lands in the connector rather than in your backlog, and your customers' connections keep working.
Does each customer connect their own ZeptoMail account?
Yes. Every customer authorises their own ZeptoMail account, so messages, meetings and notifications originate from their workspace under their permissions. You never proxy through a shared account, which also means a customer revoking access affects only their own connection.
How are duplicate notifications avoided?
Sends are deduplicated per event, so a retry after a network failure does not post the same message twice into a channel people are reading.
What can I build with the ZeptoMail integration?
A common starting point: give each customer their own mail agent and token, so their transactional mail is sent, tracked and reported entirely apart from anybody else's. Teams also use it for the other use cases listed above, and expose it to agents for governed reads and writes.
How much does the ZeptoMail integration cost?
It is included. Pricing is based on connected accounts, not on how many connectors you enable, so adding ZeptoMail does not change your per-connector cost. You can start free with 3 connected accounts.
Add ZeptoMail to your product
Start free with 3 connected accounts. No sales call required, and no per-customer integration code.