Merci Facteur
MessagingConnect AI agents to Merci Facteur, a French postal mail API that prints and sends letters through La Poste. Agents send standard, tracked, or registered letters, estimate postage, track and cancel mailings, and manage addresses so physical correspondence runs from the same workflows as digital channels.
What This Integration Enables
Merci Facteur prints a PDF and posts it through La Poste, and every design decision on this connector follows from the fact that the output is a physical object. Send Letter takes publicly reachable PDF file URLs, up to ten files per mailing, and hands them to a print and post pipeline. Sender and recipient must already exist in the address book, which is a constraint worth appreciating rather than routing around: an address that has been created deliberately and reused is a materially different thing from one assembled on the fly by a flow that has never been checked. Create Address and List Addresses maintain that book, and most operations run under a user identifier that Get User ID resolves once from an email address and everything afterward reuses.
The part that makes this more than a printing service is the delivery mode. The same PDF can go out as a standard green letter, as tracked mail, as registered mail with acknowledgment of receipt, as registered mail with electronic acknowledgment under eIDAS, or as electronic registered mail with a one time code delivered by email or SMS. Those are not postage tiers. They are different answers to the question of what evidence exists afterward that the letter was sent and received, and the vendor positions the registered modes for legally significant documents specifically. An agent can carry a document all the way to the point of dispatch, but which mode a given document requires is a question about obligation and risk, and it belongs to the people who own the document rather than to the flow that is moving it.
The operational surface around that is deliberately practical. Estimate Postage Price prices a mailing before it is committed, which turns a budget rule into something a flow can actually enforce rather than report on. Track Mailing follows a letter through delivery and Get Mailing Details returns the record, so the physical leg of a process stops being a blind spot between "we sent it" and "they say they never got it". Get Account Quota reports the allowance remaining. Authentication is a two step token exchange. The connector signs the service identifier and a timestamp with your secret key, exchanges that signature for a short lived access token, and calls the API with the token, so the secret itself never travels in clear text. An optional list of authorized server addresses can further restrict where a token may be used from.
Without FlowRunner
With FlowRunner
Use Case Scenarios
A notice that leaves with the right evidentiary weight
A contracts team sends termination notices and renewal reminders that sometimes need proof of receipt and sometimes do not. When a document is finalized in DocuSign or filed in Google Drive, the agent resolves the counterparty against List Addresses and publishes the executed PDF at a URL Merci Facteur can fetch. It then calls Estimate Postage Price for the standard, tracked, and registered variants, so the choice arrives with three real numbers attached. It posts the whole case into Slack for the contract owner. Once the mode is chosen, Send Letter dispatches and the returned mailing identifier is written back onto the contract record, so the file and the physical artifact stay joined rather than being reconciled from memory a year later.
Overdue invoices that escalate onto paper
A finance team's dunning sequence runs on email until it stops working, and then it needs a channel that lands differently. When an invoice in QuickBooks Online crosses the age the team escalates at, the agent assembles the invoice PDF and the statement and checks Get Account Quota against the size of the run. It prices the batch with Estimate Postage Price, so the escalation carries a cost the controller can weigh against the receivable. Mailing identifiers land in Google Sheets beside the invoice numbers. Track Mailing then closes the loop: when La Poste reports delivery, the agent records the date on the invoice, which is the fact that matters when the conversation about the debt continues.
The address that nobody has ever checked
A batch dispatch is only as good as its worst address, and a letter to a stale one is spent postage plus a document in an envelope that somebody else opens. Before a run, the agent reconciles the recipients against List Addresses and separates them into two piles: those already in the address book, which go straight through, and those it would have to create with Create Address, which it does not create unattended. The second pile goes to a person with the source of each address named, because Merci Facteur will print whatever it is given and there is no validation step between the agent's confidence and a stranger's mailbox. Delivery confirmations from Track Mailing are relayed to the sender through Gmail once the run completes.
Human-in-Loop Highlight
Send Letter is where a workflow stops being digital, and the gate on this connector is built around the two things a print run makes permanent. The first is the delivery mode. The same PDF sent as a standard green letter and as registered mail with acknowledgment of receipt is the same words on the same paper with entirely different consequences afterward, because one produces evidence of receipt and the other does not. An agent can read a template's metadata and infer a mode, and it will be right most of the time, which is exactly what makes the wrong time expensive. The second is the document itself. Merci Facteur fetches the PDF from the URL at print time, so what gets committed to paper is whatever is at that address in that instant, and there is no revision after ink.
So the agent does the entire preparation and stops on those two. Into Slack: "Termination notice for Dumont SARL is ready to post. Recipient resolved to an existing address book entry, last used 2026-05-19. Document is the countersigned version, SHA-256 ending 4f7c1a, which matches what was approved in the contract record. Estimate Postage Price: standard 1.86 EUR, tracked 5.40 EUR, registered with acknowledgment of receipt 7.95 EUR. Account quota after send is fine at any of the three. This notice has a response deadline in the contract, which is usually the reason a registered mode gets picked, but I am not the one who should decide that. Which mode, and is 4f7c1a the version that goes? Cancel Mailing works only until La Poste takes the envelope."
That message is the shape human-in-the-loop takes when the downstream action cannot be undone at all, which is the reason Orchestration as a Service treats a stop as a feature rather than a failure. The agent resolved the address, verified the document against an approved fingerprint, priced three real options, and checked the quota. What it handed over is the judgment call, framed with the fact that makes it urgent: Cancel Mailing is itself irreversible and only succeeds while the mailing has not yet been handed to the carrier, so the exit exists for a while and then it does not. Create Address sits on the same side of the line for a smaller reason that adds up over a batch, which is that an unverified address is postage spent on a document arriving somewhere it should not. These are automation exceptions in the literal sense: the flow handles the volume, and a person handles the ones where being wrong is not recoverable.
Agent Capabilities
11 actionsMailing
6- Send Letter Prints and posts PDF documents through La Poste, accepting up to ten publicly reachable file URLs in one mailing. The delivery mode is chosen per mailing: standard green letter, tracked, registered with acknowledgment of receipt, registered with electronic acknowledgment under eIDAS, or electronic registered mail with a one time code delivered by email or SMS. Sender and recipient must already exist in the address book, and Merci Facteur fetches each PDF at print time, so the version that goes out is the version living at that URL when the request is processed.
- Estimate Postage Price Returns the price of a mailing before it is sent, which is what turns a budget rule into something a flow can enforce rather than report on afterward. Pricing each candidate delivery mode is also how a person is given a real choice rather than an abstract one.
- List Mailings Returns the account's mailings, which is how a flow reconciles what was actually posted against what a source system believes it sent.
- Get Mailing Details Retrieves the full record of one mailing, including how it was sent and to whom. This is the artifact that answers a question about a letter months after the letter left.
- Track Mailing Retrieves current delivery status for a mailing from La Poste. With no triggers on this service, this is the polling read that closes the loop between dispatch and delivery instead of leaving the physical leg of a process unobserved.
- Cancel Mailing Withdraws a mailing before it is handed to La Poste. It is itself irreversible and it only succeeds inside that window, so any workflow that expects to be able to stop a send should state the deadline at the moment it proposes one.
Addresses
2- Create Address Adds a sender or recipient to the address book, with the country validated against the set of names Merci Facteur accepts. Because printing happens against whatever address is stored, creating one is the moment an unverified address becomes a mailable one.
- List Addresses Returns the address book, which is how a flow resolves a recipient to an entry that already exists rather than manufacturing a new one for every send.
Account
3- Get Account Quota Reports the account's remaining mailing allowance, which is the check that belongs in front of a batch rather than in the middle of one.
- Get User ID Resolves the user identifier from an email address. Nearly every other operation needs it, so resolve it once and reuse it rather than paying for the lookup on every letter.
- Create User Provisions a user under the account, which is how a multi entity or multi client setup keeps each sender's mailings and address book separate.
Frequently Asked Questions
What can FlowRunner do with Merci Facteur?
FlowRunner agents can run Send Letter, Estimate Postage Price, and List Mailings in Merci Facteur, plus 8 more actions.
Does connecting Merci Facteur to FlowRunner require OAuth?
Merci Facteur uses a custom authentication method to connect to FlowRunner.
Can Merci Facteur trigger a FlowRunner workflow automatically?
Merci Facteur doesn't currently expose triggers in FlowRunner. It connects as an action step inside workflows started by another trigger.
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