Transactional Email · Integration
Mandrill
Add Mandrill to your product for your customers, and give your AI agents governed access to it.
Mandrill is Mailchimp's transactional email service and its API at mandrillapp.com/api/1.0 is unusual: every call is a POST with a JSON body that carries the key field inline, and there are no HTTP auth headers or GET endpoints. It is a paid add-on to a Mailchimp account rather than a standalone product, so an API key only exists once blocks of sends have been purchased. Messages are sent through messages/send or messages/send-template, where template content uses mc:edit regions and merge variables supplied per recipient in merge_vars. Delivery outcomes are read from messages/search, which only covers a rolling recent window, so long-term reporting needs webhooks or the export endpoints instead. Rejection lists for bounces and spam complaints are a separate resource that silently suppresses future sends to an address until you remove the entry, which is the usual explanation for mail that appears accepted but never arrives. fastn holds each customer's Mandrill key and subaccount separately and handles the per-tenant auth and upkeep.
In your product
Embedded for your customers. Per-tenant auth, no per-customer code, maintained by fastn.
Let a customer connect their own Mandrill account so transactional mail leaves on their domain and reputation
Send templated notifications from your product with per-recipient merge variables
Show bounce, open and click events for each message next to the record that triggered it
Let a customer inspect and clear their rejection list when a valid address has been suppressed
For your AI agents
Governed, audited access for the agents you build, through the MCP server.
Let an agent look up why a specific message was not delivered and check the rejection list, audited per tenant
Have an agent resend a failed transactional message only after a human confirms the recipient
Give an agent read access to template content so it can explain what a customer will receive
Example prompt
Why did the password reset email to this address never arrive from Mandrill?
Set up Mandrill in 4 steps
- 01Enable the Mandrill connector from your fastn dashboard.
- 02Have each customer authorise their own Mandrill account, so calls run under their credentials rather than a shared key.
- 03Decide which messages, templates and delivery events your product needs, map those fields, then enable the actions and triggers you want.
- 04Call it from your product and expose it to your agents through the same governed connection.
Why teams use the Mandrill integration
What you get by embedding it with fastn instead of building it yourself.
- Ship a Mandrill integration without building it. Your customers connect their own Mandrill account inside your product and work their messages, templates and delivery events there, with no per-customer code on your side.
- Handle the part that actually costs time: deliverability is the whole game, and it is decided by bounces, complaints and the reputation of the sending domain rather than by anything in the send call. fastn owns the auth, token refresh, rate limits, pagination and breaking-change fixes, so a Mandrill update is not your on-call problem.
- One integration serves your product and your agents. The same governed Mandrill connection powers in-product features and gives AI agents scoped, audited access, so you send the mail your product owes its users and know what happened to it without wiring it twice.
Used by these teams
Compare with
Amazon SES
Resend
MailgunOften used alongside
Tools the same teams tend to run next to Mandrill, across other categories.
Notion
Box
Shopify
StripeMandrill integration FAQ
How do I add a Mandrill integration to my product?
Enable the Mandrill connector in your fastn dashboard, then let each customer authenticate their own Mandrill account. fastn handles the OAuth flow, token storage and refresh per tenant, so there is no Mandrill client code in your app and no per-customer branch in your codebase. Setup is 4 steps.
Do my customers each connect their own Mandrill account?
Yes. Every connection is scoped to the individual customer, so each authorises their own Mandrill account and only ever sees their own messages, templates and delivery events. 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 Mandrill integration?
Yes. The same connection is exposed to your agents through the fastn MCP gateway, with permissions scoped per tenant and every call audited. Let an agent look up why a specific message was not delivered and check the rejection list, audited per tenant
Who maintains the Mandrill integration?
fastn does. When Mandrill 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.
Can each customer send from their own domain with Mandrill?
Yes, and it is the reason to do this per tenant rather than through one shared key. Sending reputation attaches to the domain, so a customer sending from their own verified domain in Mandrill carries their own deliverability rather than inheriting yours or damaging it.
How do bounces and complaints come back from Mandrill?
As records rather than log lines. Hard bounces, spam complaints and unsubscribes become suppression state you can read per tenant, so your product can stop mailing an address that already failed instead of sending into a hole and quietly burning the customer's sending reputation.
What can I build with the Mandrill integration?
A common starting point: let a customer connect their own Mandrill account so transactional mail leaves on their domain and reputation. 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 Mandrill integration cost?
It is included. Pricing is based on connected accounts, not on how many connectors you enable, so adding Mandrill does not change your per-connector cost. You can start free with 3 connected accounts.
Add Mandrill to your product
Start free with 3 connected accounts. No sales call required, and no per-customer integration code.