Send with a tenant

covers the concepts behind this page.

The user determines who receives the message. The tenant determines which of that user’s contexts Courier builds it from: whose brand, whose defaults, whose content. You can target a single user in a tenant’s context, fan out to every member of a tenant, or walk a tenant hierarchy up or down. The tenant goes in one of two places, and both behave identically. Put it on the recipient as to.tenant_id, or on the message as context.tenant_id. Pick one and put it behind a shared helper, because tracking down a message that rendered with the wrong brand is a great deal harder when two call sites disagree about where the tenant lives.

Prerequisites

Send to a user with tenant context

Set context.tenant_id on a recipient to attach the tenant’s metadata, preferences, and branding to their message. User-level preferences and profile data take precedence over the tenant’s. The template holds the content. Pass the variables it expects in data, and reference tenant values like {$.tenant.name} from inside the template, where the tenant context resolves them.

import Courier from '@trycourier/courier';

const client = new Courier({
  apiKey: process.env['COURIER_API_KEY'],
});

const { requestId } = await client.send.message({
  message: {
    to: {
      user_id: 'user_123',
      context: { tenant_id: 'acme-corp' },
    },
    template: 'nt_01kx4h2jdafq8bk9aftxak4b40',
    data: { first_name: 'Sarah' },
    routing: { method: 'single', channels: ['inbox'] },
  },
});

console.log(requestId);

import os
from courier import Courier

client = Courier(
    api_key=os.environ.get("COURIER_API_KEY"),
)
response = client.send.message(
    message={
        "to": {
            "user_id": "user_123",
            "context": {"tenant_id": "acme-corp"},
        },
        "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
        "data": {"first_name": "Sarah"},
        "routing": {"method": "single", "channels": ["inbox"]},
    },
)
print(response.request_id)

curl -X POST https://api.courier.com/send \
  -H "Authorization: Bearer $COURIER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "message": {
      "to": { "user_id": "user_123", "context": { "tenant_id": "acme-corp" } },
      "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
      "data": { "first_name": "Sarah" },
      "routing": { "method": "single", "channels": ["inbox"] }
    }
  }'

require "courier"

courier = Courier::Client.new(api_key: ENV["COURIER_API_KEY"])

response = courier.send_.message(
  message: {
    to: {
      user_id: "user_123",
      context: { tenant_id: "acme-corp" }
    },
    template: "nt_01kx4h2jdafq8bk9aftxak4b40",
    data: { first_name: "Sarah" },
    routing: { method: "single", channels: ["inbox"] }
  }
)

puts(response)

response, err := client.Send.Message(context.TODO(), courier.SendMessageParams{
	Message: courier.SendMessageParamsMessage{
		To: courier.SendMessageParamsMessageToUnion{
			OfUserRecipient: &shared.UserRecipientParam{
				UserID:  courier.String("user_123"),
				Context: shared.MessageContextParam{TenantID: courier.String("acme-corp")},
			},
		},
		Template: courier.String("nt_01kx4h2jdafq8bk9aftxak4b40"),
		Data: map[string]any{
			"first_name": "Sarah",
		},
		Routing: courier.SendMessageParamsMessageRouting{
			Method:   string(shared.MessageRoutingMethodSingle),
			Channels: []shared.MessageRoutingChannelUnionParam{{OfString: courier.String("inbox")}},
		},
	},
})

SendMessageParams params = SendMessageParams.builder()
    .message(SendMessageParams.Message.builder()
        .to(JsonValue.from(java.util.Map.of(
            "user_id", "user_123",
            "context", java.util.Map.of("tenant_id", "acme-corp"))))
        .template("nt_01kx4h2jdafq8bk9aftxak4b40")
        .data(JsonValue.from(java.util.Map.of("first_name", "Sarah")))
        .routing(JsonValue.from(java.util.Map.of(
            "method", "single",
            "channels", java.util.List.of("inbox"))))
        .build())
    .build();
client.send().message(params);

$response = $client->send->message(
  message: [
    'to' => [
      'userID' => 'user_123',
      'context' => ['tenantID' => 'acme-corp'],
    ],
    'template' => 'nt_01kx4h2jdafq8bk9aftxak4b40',
    'data' => ['first_name' => 'Sarah'],
    'routing' => ['method' => 'single', 'channels' => ['inbox']],
  ],
);

SendMessageParams parameters = new()
{
    Message = new()
    {
        To = new UserRecipient { UserID = "user_123", Context = new MessageContext { TenantID = "acme-corp" } },
        Template = "nt_01kx4h2jdafq8bk9aftxak4b40",
        Data = new Dictionary<string, JsonElement>()
        {
            { "first_name", JsonSerializer.SerializeToElement("Sarah") },
        },
        Routing = new Routing { Method = Method.Single, Channels = ["inbox"] },
    },
};

await client.Send.Message(parameters);

courier send message \
  --api-key "$COURIER_API_KEY" \
  --message '{"to":{"user_id":"user_123","context":{"tenant_id":"acme-corp"}},"template":"nt_01kx4h2jdafq8bk9aftxak4b40","data":{"first_name":"Sarah"},"routing":{"method":"single","channels":["inbox"]}}'

With Courier MCP, send my nt_01kx4h2jdafq8bk9aftxak4b40 template to user_123 with acme-corp as their tenant context.

A user does not need to be a member of the tenant to receive a message in its context. This is useful when the tenant holds branding or credentials but you are not fanning out to members.

Send to every member of a tenant

Put a tenant_id in to and Courier looks up the tenant’s members and sends to each one.

import Courier from '@trycourier/courier';

const client = new Courier({
  apiKey: process.env['COURIER_API_KEY'],
});

const { requestId } = await client.send.message({
  message: {
    to: { tenant_id: 'acme-corp' },
    template: 'nt_01kx4h2jdafq8bk9aftxak4b40',
    data: { first_name: 'Sarah' },
    routing: { method: 'single', channels: ['inbox'] },
  },
});

console.log(requestId);

import os
from courier import Courier

client = Courier(
    api_key=os.environ.get("COURIER_API_KEY"),
)
response = client.send.message(
    message={
        "to": {"tenant_id": "acme-corp"},
        "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
        "data": {"first_name": "Sarah"},
        "routing": {"method": "single", "channels": ["inbox"]},
    },
)
print(response.request_id)

curl -X POST https://api.courier.com/send \
  -H "Authorization: Bearer $COURIER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "message": {
      "to": { "tenant_id": "acme-corp" },
      "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
      "data": { "first_name": "Sarah" },
      "routing": { "method": "single", "channels": ["inbox"] }
    }
  }'

require "courier"

courier = Courier::Client.new(api_key: ENV["COURIER_API_KEY"])

response = courier.send_.message(
  message: {
    to: { tenant_id: "acme-corp" },
    template: "nt_01kx4h2jdafq8bk9aftxak4b40",
    data: { first_name: "Sarah" },
    routing: { method: "single", channels: ["inbox"] }
  }
)

puts(response)

response, err := client.Send.Message(context.TODO(), courier.SendMessageParams{
	Message: courier.SendMessageParamsMessage{
		To: courier.SendMessageParamsMessageToUnion{
			OfUserRecipient: &shared.UserRecipientParam{
				TenantID: courier.String("acme-corp"),
			},
		},
		Template: courier.String("nt_01kx4h2jdafq8bk9aftxak4b40"),
		Data: map[string]any{
			"first_name": "Sarah",
		},
		Routing: courier.SendMessageParamsMessageRouting{
			Method:   string(shared.MessageRoutingMethodSingle),
			Channels: []shared.MessageRoutingChannelUnionParam{{OfString: courier.String("inbox")}},
		},
	},
})

SendMessageParams params = SendMessageParams.builder()
    .message(SendMessageParams.Message.builder()
        .to(JsonValue.from(java.util.Map.of("tenant_id", "acme-corp")))
        .template("nt_01kx4h2jdafq8bk9aftxak4b40")
        .data(JsonValue.from(java.util.Map.of("first_name", "Sarah")))
        .routing(JsonValue.from(java.util.Map.of(
            "method", "single",
            "channels", java.util.List.of("inbox"))))
        .build())
    .build();
client.send().message(params);

$response = $client->send->message(
  message: [
    'to' => ['tenantID' => 'acme-corp'],
    'template' => 'nt_01kx4h2jdafq8bk9aftxak4b40',
    'data' => ['first_name' => 'Sarah'],
    'routing' => ['method' => 'single', 'channels' => ['inbox']],
  ],
);

SendMessageParams parameters = new()
{
    Message = new()
    {
        To = new UserRecipient { TenantID = "acme-corp" },
        Template = "nt_01kx4h2jdafq8bk9aftxak4b40",
        Data = new Dictionary<string, JsonElement>()
        {
            { "first_name", JsonSerializer.SerializeToElement("Sarah") },
        },
        Routing = new Routing { Method = Method.Single, Channels = ["inbox"] },
    },
};

await client.Send.Message(parameters);

courier send message \
  --api-key "$COURIER_API_KEY" \
  --message '{"to":{"tenant_id":"acme-corp"},"template":"nt_01kx4h2jdafq8bk9aftxak4b40","data":{"first_name":"Sarah"},"routing":{"method":"single","channels":["inbox"]}}'

With Courier MCP, send my nt_01kx4h2jdafq8bk9aftxak4b40 template to every member of acme-corp.

Send to multiple users with shared context

When sending to an array of users, set a shared tenant at the message level with message.context.tenant_id. Every recipient inherits it. Override it for a specific recipient by setting context.tenant_id on that entry, which takes precedence over the message-level context.

import Courier from '@trycourier/courier';

const client = new Courier({
  apiKey: process.env['COURIER_API_KEY'],
});

const { requestId } = await client.send.message({
  message: {
    template: 'nt_01kx4h2jdafq8bk9aftxak4b40',
    context: { tenant_id: 'acme-corp' },
    to: [
      { user_id: 'user_123' },
      { user_id: 'user_456' },
      { user_id: 'user_456', context: { tenant_id: 'beta-inc' } },
    ],
  },
});

console.log(requestId);

import os
from courier import Courier

client = Courier(
    api_key=os.environ.get("COURIER_API_KEY"),
)
response = client.send.message(
    message={
        "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
        "context": {"tenant_id": "acme-corp"},
        "to": [
            {"user_id": "user_123"},
            {"user_id": "user_456"},
            {"user_id": "user_456", "context": {"tenant_id": "beta-inc"}},
        ],
    },
)
print(response.request_id)

curl -X POST https://api.courier.com/send \
  -H "Authorization: Bearer $COURIER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "message": {
      "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
      "context": { "tenant_id": "acme-corp" },
      "to": [
        { "user_id": "user_123" },
        { "user_id": "user_456" },
        { "user_id": "user_456", "context": { "tenant_id": "beta-inc" } }
      ]
    }
  }'

require "courier"

courier = Courier::Client.new(api_key: ENV["COURIER_API_KEY"])

response = courier.send_.message(
  message: {
    template: "nt_01kx4h2jdafq8bk9aftxak4b40",
    context: { tenant_id: "acme-corp" },
    to: [
      { user_id: "user_123" },
      { user_id: "user_456" },
      { user_id: "user_456", context: { tenant_id: "beta-inc" } }
    ]
  }
)

puts(response)

response, err := client.Send.Message(context.TODO(), courier.SendMessageParams{
	Message: courier.SendMessageParamsMessage{
		Template: courier.String("nt_01kx4h2jdafq8bk9aftxak4b40"),
		Context:  shared.MessageContextParam{TenantID: courier.String("acme-corp")},
		To: courier.SendMessageParamsMessageToUnion{
			OfSendMessagesMessageToArray: []courier.SendMessageParamsMessageToArrayItemUnion{
				{OfUserRecipient: &shared.UserRecipientParam{UserID: courier.String("user_123")}},
				{OfUserRecipient: &shared.UserRecipientParam{UserID: courier.String("user_456")}},
				{OfUserRecipient: &shared.UserRecipientParam{
					UserID:  courier.String("user_456"),
					Context: shared.MessageContextParam{TenantID: courier.String("beta-inc")},
				}},
			},
		},
	},
})

SendMessageParams params = SendMessageParams.builder()
    .message(SendMessageParams.Message.builder()
        .template("nt_01kx4h2jdafq8bk9aftxak4b40")
        .context(JsonValue.from(java.util.Map.of("tenant_id", "acme-corp")))
        .to(JsonValue.from(java.util.List.of(
            java.util.Map.of("user_id", "user_123"),
            java.util.Map.of("user_id", "user_456"),
            java.util.Map.of("user_id", "user_456", "context", java.util.Map.of("tenant_id", "beta-inc")))))
        .build())
    .build();
client.send().message(params);

$response = $client->send->message(
  message: [
    'template' => 'nt_01kx4h2jdafq8bk9aftxak4b40',
    'context' => ['tenantID' => 'acme-corp'],
    'to' => [
      ['userID' => 'user_123'],
      ['userID' => 'user_456'],
      ['userID' => 'user_456', 'context' => ['tenantID' => 'beta-inc']],
    ],
  ],
);

SendMessageParams parameters = new()
{
    Message = new()
    {
        Template = "nt_01kx4h2jdafq8bk9aftxak4b40",
        Context = new MessageContext { TenantID = "acme-corp" },
        To = new List<Recipient>
        {
            new UserRecipient { UserID = "user_123" },
            new UserRecipient { UserID = "user_456" },
            new UserRecipient { UserID = "user_456", Context = new MessageContext { TenantID = "beta-inc" } },
        },
    },
};

await client.Send.Message(parameters);

courier send message \
  --api-key "$COURIER_API_KEY" \
  --message '{"template":"nt_01kx4h2jdafq8bk9aftxak4b40","context":{"tenant_id":"acme-corp"},"to":[{"user_id":"user_123"},{"user_id":"user_456"},{"user_id":"user_456","context":{"tenant_id":"beta-inc"}}]}'

With Courier MCP, send my nt_01kx4h2jdafq8bk9aftxak4b40 template to user_123 and user_456 in acme-corp, and user_456 in beta-inc.

Here user_123 and user_456 get Acme Corp’s context, while user_456 gets Beta Inc’s.

Handle users in multiple tenants

Courier infers the tenant for a user who belongs to exactly one tenant, so specifying it is optional for them. A user with two or more memberships must have context.tenant_id set, or the send returns Tenant Context Not Found.

In the tenant/<template_id> format, tenant is the literal word rather than your tenant ID, which goes in context.tenant_id. has the full format.

Fan out across a hierarchy

Set include_children: true to also send to users in a tenant’s descendant tenants, or include_parent: true to walk upward through its ancestors.

import Courier from '@trycourier/courier';

const client = new Courier({
  apiKey: process.env['COURIER_API_KEY'],
});

const { requestId } = await client.send.message({
  message: {
    to: { tenant_id: 'acme-corp', include_children: true },
    template: 'nt_01kx4h2jdafq8bk9aftxak4b40',
    routing: { method: 'single', channels: ['inbox'] },
  },
});

console.log(requestId);

import os
from courier import Courier

client = Courier(
    api_key=os.environ.get("COURIER_API_KEY"),
)
response = client.send.message(
    message={
        "to": {"tenant_id": "acme-corp", "include_children": True},
        "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
        "routing": {"method": "single", "channels": ["inbox"]},
    },
)
print(response.request_id)

curl -X POST https://api.courier.com/send \
  -H "Authorization: Bearer $COURIER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "message": {
      "to": { "tenant_id": "acme-corp", "include_children": true },
      "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
      "routing": { "method": "single", "channels": ["inbox"] }
    }
  }'

require "courier"

courier = Courier::Client.new(api_key: ENV["COURIER_API_KEY"])

response = courier.send_.message(
  message: {
    to: { tenant_id: "acme-corp", include_children: true },
    template: "nt_01kx4h2jdafq8bk9aftxak4b40",
    routing: { method: "single", channels: ["inbox"] }
  }
)

puts(response)

// include_children isn't in the typed recipient model, so set it as an extra field.
to := shared.UserRecipientParam{}
to.SetExtraFields(map[string]any{
	"tenant_id":        "acme-corp",
	"include_children": true,
})

response, err := client.Send.Message(context.TODO(), courier.SendMessageParams{
	Message: courier.SendMessageParamsMessage{
		To:       courier.SendMessageParamsMessageToUnion{OfUserRecipient: &to},
		Template: courier.String("nt_01kx4h2jdafq8bk9aftxak4b40"),
		Routing: courier.SendMessageParamsMessageRouting{
			Method:   string(shared.MessageRoutingMethodSingle),
			Channels: []shared.MessageRoutingChannelUnionParam{{OfString: courier.String("inbox")}},
		},
	},
})

SendMessageParams params = SendMessageParams.builder()
    .message(SendMessageParams.Message.builder()
        .to(JsonValue.from(java.util.Map.of(
            "tenant_id", "acme-corp",
            "include_children", true)))
        .template("nt_01kx4h2jdafq8bk9aftxak4b40")
        .routing(JsonValue.from(java.util.Map.of(
            "method", "single",
            "channels", java.util.List.of("inbox"))))
        .build())
    .build();
client.send().message(params);

$response = $client->send->message(
  message: [
    'to' => ['tenantID' => 'acme-corp', 'include_children' => true],
    'template' => 'nt_01kx4h2jdafq8bk9aftxak4b40',
    'routing' => ['method' => 'single', 'channels' => ['inbox']],
  ],
);

// include_children isn't in the typed recipient model, so build `to` from raw JSON.
SendMessageParams parameters = new()
{
    Message = new()
    {
        To = UserRecipient.FromRawUnchecked(new Dictionary<string, JsonElement>
        {
            ["tenant_id"] = JsonSerializer.SerializeToElement("acme-corp"),
            ["include_children"] = JsonSerializer.SerializeToElement(true),
        }),
        Template = "nt_01kx4h2jdafq8bk9aftxak4b40",
        Routing = new Routing { Method = Method.Single, Channels = ["inbox"] },
    },
};

var response = await client.Send.Message(parameters);

courier send message \
  --api-key "$COURIER_API_KEY" \
  --message '{"to":{"tenant_id":"acme-corp","include_children":true},"template":"nt_01kx4h2jdafq8bk9aftxak4b40","routing":{"method":"single","channels":["inbox"]}}'

With Courier MCP, send my nt_01kx4h2jdafq8bk9aftxak4b40 template to acme-corp and all of its child tenants.

Courier traverses up to four levels of the hierarchy in either direction.

On Go and C#, include_children and include_parent aren’t in the typed recipient models yet, so the tabs above set them as extra fields on the recipient. Every other operation on this page has a fully typed Go and C# form.

Segment delivery data by customer

Courier records the tenant on the message at providers[].reference.tenantId, so you can group logs and delivery data by customer after the fact. Read it from the or from a . A send that never named a tenant carries no reference, which is one more reason to route every multi-tenant send through the same helper.

Limits & behavior

None of these raise an error, which is what makes them worth knowing before you ship.

Courier can apply a tenant you did not name. If the user belongs to exactly one tenant and the send specifies none, Courier loads that tenant’s context anyway. See , and turn it off in workspace settings if you would rather send unscoped.
A tenant-scoped inbox message is invisible to a client signed in without the tenant. The send reports success and the feed stays empty. Pass the same tenantId to signIn that your sends carry.
Hierarchy traversal stops at four levels. The window starts at the tenant you sent to rather than at the root, so a fifth ancestor’s settings never reach the message.

Verify

Send with a branded tenant

Send with a tenant that has a brand_id set, and confirm the message renders with that tenant’s brand (see ).

Check the message log

Confirm the send used the tenant’s preferences, not the workspace defaults.

Confirm fan-out delivery

For a fan-out send, confirm each expected member received a copy.

Get started

Send messages

Journeys

Broadcasts

Design

Recipients

Tenants

Monitoring

Workspaces

Resources

Send with a tenant

Prerequisites

Send to a user with tenant context

Send to every member of a tenant

Send to multiple users with shared context

Handle users in multiple tenants

Fan out across a hierarchy

Segment delivery data by customer

Limits & behavior

Verify

​Prerequisites

​Send to a user with tenant context

​Send to every member of a tenant

​Send to multiple users with shared context

​Handle users in multiple tenants

​Fan out across a hierarchy

​Segment delivery data by customer

​Limits & behavior

​Verify

Prerequisites

Send to a user with tenant context

Send to every member of a tenant

Send to multiple users with shared context

Handle users in multiple tenants

Fan out across a hierarchy

Segment delivery data by customer

Limits & behavior

Verify