Email providers

Available providers

Amazon SES

SendGrid

Postmark

Mailgun

Resend

SMTP

Mandrill

SparkPost

Mailjet

MailerSend

Amply

Gmail

OneSignal

is the generic relay for any server that speaks it. is OAuth-based and suits testing rather than volume.

Profile requirements

Every email provider addresses the recipient the same way, by email address, so the profile you send to needs an email. Store it once with , which merges into the profile and creates it if it does not exist:

const profile = await client.profiles.create('user_123', {
  profile: {
    email: 'sarah@acme-corp.com',
  },
});

profile = client.profiles.create(
    user_id="user_123",
    profile={
        "email": "sarah@acme-corp.com",
    },
)

curl --request POST \
  --url https://api.courier.com/profiles/user_123 \
  --header "Authorization: Bearer $COURIER_API_KEY" \
  --header 'Content-Type: application/json' \
  --data '{
    "profile": {
      "email": "sarah@acme-corp.com"
    }
  }'

profile = courier.profiles.create(
  "user_123",
  profile: {
    email: "sarah@acme-corp.com"
  }
)

profile, err := client.Profiles.New(
	context.TODO(),
	"user_123",
	courier.ProfileNewParams{
		Profile: map[string]any{
			"email": "sarah@acme-corp.com",
		},
	},
)

ProfileCreateParams params = ProfileCreateParams.builder()
    .userId("user_123")
    .profile(ProfileCreateParams.Profile.builder()
        .putAdditionalProperty("email", JsonValue.from("sarah@acme-corp.com"))
        .build())
    .build();
ProfileCreateResponse profile = client.profiles().create(params);

$profile = $client->profiles->create('user_123', profile: [
  'email' => 'sarah@acme-corp.com',
]);

ProfileCreateParams parameters = new()
{
    UserID = "user_123",
    Profile = new Dictionary<string, JsonElement>()
    {
        { "email", JsonSerializer.SerializeToElement("sarah@acme-corp.com") },
    },
};
var profile = await client.Profiles.Create(parameters);

courier profiles create \
  --api-key "$COURIER_API_KEY" \
  --user-id user_123 \
  --profile '{"email":"sarah@acme-corp.com"}'

With Courier MCP, create a profile for user_123 with the email sarah@acme-corp.com.

A provider that also accepts an inline address still reads email off the profile when you send to a user_id, which is what lets preferences apply and lets the address change without touching your send code.

Send to a recipient

Send to user id
Send to email

Courier reads email off the saved profile, so preferences apply and the address can change without touching this code.

const { requestId } = await courier.send.message({
  message: {
    to: {
      user_id: "user_123",
    },
    template: "nt_01kx4h2jdafq8bk9aftxak4b40",
  },
});

response = client.send.message(
    message={
        "to": {
            "user_id": "user_123",
        },
        "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
    },
)

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"
      },
      "template": "nt_01kx4h2jdafq8bk9aftxak4b40"
    }
  }'

response = courier.send_.message(
  message: {
    to: {
      user_id: "user_123"
    },
    template: "nt_01kx4h2jdafq8bk9aftxak4b40"
  }
)

response, err := client.Send.Message(context.TODO(), courier.SendMessageParams{
	Message: courier.SendMessageParamsMessage{
		To: courier.SendMessageParamsMessageToUnion{
			OfUserRecipient: &shared.UserRecipientParam{
				UserID: courier.String("user_123"),
			},
		},
		Template: courier.String("nt_01kx4h2jdafq8bk9aftxak4b40"),
	},
})

SendMessageParams params = SendMessageParams.builder()
    .message(SendMessageParams.Message.builder()
        .to(UserRecipient.builder().userId("user_123").build())
        .template("nt_01kx4h2jdafq8bk9aftxak4b40")
        .build())
    .build();
SendMessageResponse response = client.send().message(params);

$response = $client->send->message(
  message: [
    'to' => [
      'user_id' => 'user_123',
    ],
    'template' => 'nt_01kx4h2jdafq8bk9aftxak4b40',
  ],
);

SendMessageParams parameters = new()
{
    Message = new()
    {
        To = new UserRecipient { UserID = "user_123" },
        Template = "nt_01kx4h2jdafq8bk9aftxak4b40",
    },
};

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

courier send message \
  --api-key "$COURIER_API_KEY" \
  --message.to '{"user_id": "user_123"}' \
  --message.template nt_01kx4h2jdafq8bk9aftxak4b40

With Courier MCP, send my template to user_123 by email.

A one-off to an address you are not storing. No profile is created, so no preference applies.

const { requestId } = await courier.send.message({
  message: {
    to: {
      email: "sarah@acme-corp.com",
    },
    template: "nt_01kx4h2jdafq8bk9aftxak4b40",
  },
});

response = client.send.message(
    message={
        "to": {
            "email": "sarah@acme-corp.com",
        },
        "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
    },
)

curl -X POST https://api.courier.com/send \
  -H "Authorization: Bearer $COURIER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "message": {
      "to": {
        "email": "sarah@acme-corp.com"
      },
      "template": "nt_01kx4h2jdafq8bk9aftxak4b40"
    }
  }'

response = courier.send_.message(
  message: {
    to: {
      email: "sarah@acme-corp.com"
    },
    template: "nt_01kx4h2jdafq8bk9aftxak4b40"
  }
)

response, err := client.Send.Message(context.TODO(), courier.SendMessageParams{
	Message: courier.SendMessageParamsMessage{
		To: courier.SendMessageParamsMessageToUnion{
			OfUserRecipient: &shared.UserRecipientParam{
				Email: courier.String("sarah@acme-corp.com"),
			},
		},
		Template: courier.String("nt_01kx4h2jdafq8bk9aftxak4b40"),
	},
})

SendMessageParams params = SendMessageParams.builder()
    .message(SendMessageParams.Message.builder()
        .to(UserRecipient.builder().email("sarah@acme-corp.com").build())
        .template("nt_01kx4h2jdafq8bk9aftxak4b40")
        .build())
    .build();
SendMessageResponse response = client.send().message(params);

$response = $client->send->message(
  message: [
    'to' => [
      'email' => 'sarah@acme-corp.com',
    ],
    'template' => 'nt_01kx4h2jdafq8bk9aftxak4b40',
  ],
);

SendMessageParams parameters = new()
{
    Message = new()
    {
        To = new UserRecipient { Email = "sarah@acme-corp.com" },
        Template = "nt_01kx4h2jdafq8bk9aftxak4b40",
    },
};

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

courier send message \
  --api-key "$COURIER_API_KEY" \
  --message.to '{"email": "sarah@acme-corp.com"}' \
  --message.template nt_01kx4h2jdafq8bk9aftxak4b40

With Courier MCP, send my template to sarah@acme-corp.com by email.

Channel overrides

covers the two levels and which one wins. These are the fields an email channel override accepts. The sender is the field most often overridden. With no override and no template From, an email goes out as the From Address on the provider’s integration. covers all three levels. Postmark, Amply, and MailerSend also accept a sender inside a provider override at override.config.fromAddress. On MailerSend that value beats a channel override, and on the other two the channel override still wins.

Available channel override fields

Every field you can set in message.channels.email.override. All are optional.

Field	Type	Description
`subject`	string	Overrides the email subject line.
`from`	string	Sender address. Accepts a plain email or `"Display Name <email>"` format.
`reply_to`	string	Sets the Reply-To header. Same format as `from`.
`cc`	string	CC recipients as a comma-separated string (e.g. `"sarah@acme-corp.com,ops@acme-corp.com"`).
`bcc`	string	BCC recipients as a comma-separated string. Courier converts this to an array for providers that require it.
`html`	string	Replaces the rendered HTML body entirely.
`text`	string	Replaces the plain-text body.
`attachments`	array	File attachments. Schema varies by provider. See the provider page.
`brand`	object	Overrides brand settings (logo, colors). Uses the same schema as .
`tracking`	object	Controls tracking behavior. Set `{ "open": false }` to disable open tracking.

Set any of them under channels.email.override on the send. The table above is the full list:

const { requestId } = await courier.send.message({
  message: {
    to: { email: 'sarah@acme-corp.com' },
    template: 'nt_01kx4h2jdafq8bk9aftxak4b40',
    channels: {
      email: {
        override: {
          subject: 'Your order has shipped',
          reply_to: 'support@acme-corp.com',
        },
      },
    },
  },
});

response = client.send.message(
    message={
        "to": {"email": "sarah@acme-corp.com"},
        "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
        "channels": {
            "email": {
                "override": {
                    "subject": "Your order has shipped",
                    "reply_to": "support@acme-corp.com",
                },
            },
        },
    },
)

curl -X POST https://api.courier.com/send \
  -H "Authorization: Bearer $COURIER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "message": {
      "to": { "email": "sarah@acme-corp.com" },
      "template": "nt_01kx4h2jdafq8bk9aftxak4b40",
      "channels": {
        "email": {
          "override": {
            "subject": "Your order has shipped",
            "reply_to": "support@acme-corp.com"
          }
        }
      }
    }
  }'

response = courier.send_.message(
  message: {
    to: { email: "sarah@acme-corp.com" },
    template: "nt_01kx4h2jdafq8bk9aftxak4b40",
    channels: {
      email: {
        override: {
          subject: "Your order has shipped",
          reply_to: "support@acme-corp.com"
        }
      }
    }
  }
)

response, err := client.Send.Message(context.TODO(), courier.SendMessageParams{
	Message: courier.SendMessageParamsMessage{
		To: courier.SendMessageParamsMessageToUnion{
			OfUserRecipient: &shared.UserRecipientParam{
				Email: courier.String("sarah@acme-corp.com"),
			},
		},
		Template: courier.String("nt_01kx4h2jdafq8bk9aftxak4b40"),
		Channels: shared.MessageChannelsParam{
			"email": shared.ChannelParam{
				Override: map[string]any{
					"subject":  "Your order has shipped",
					"reply_to": "support@acme-corp.com",
				},
			},
		},
	},
})

SendMessageParams params = SendMessageParams.builder()
    .message(SendMessageParams.Message.builder()
        .to(UserRecipient.builder().email("sarah@acme-corp.com").build())
        .template("nt_01kx4h2jdafq8bk9aftxak4b40")
        .channels(MessageChannels.builder()
            .putAdditionalProperty("email", JsonValue.from(java.util.Map.of(
                "override", java.util.Map.of(
                    "subject", "Your order has shipped",
                    "reply_to", "support@acme-corp.com"))))
            .build())
        .build())
    .build();
SendMessageResponse response = client.send().message(params);

$response = $client->send->message(
  message: [
    'to' => ['email' => 'sarah@acme-corp.com'],
    'template' => 'nt_01kx4h2jdafq8bk9aftxak4b40',
    'channels' => [
      'email' => [
        'override' => [
          'subject' => 'Your order has shipped',
          'reply_to' => 'support@acme-corp.com',
        ],
      ],
    ],
  ],
);

SendMessageParams parameters = new()
{
    Message = new()
    {
        To = new UserRecipient { Email = "sarah@acme-corp.com" },
        Template = "nt_01kx4h2jdafq8bk9aftxak4b40",
        Channels = new Dictionary<string, Channel>()
        {
            {
                "email",
                new()
                {
                    Override = new Dictionary<string, JsonElement>()
                    {
                        { "subject", JsonSerializer.SerializeToElement("Your order has shipped") },
                        { "reply_to", JsonSerializer.SerializeToElement("support@acme-corp.com") },
                    },
                }
            },
        },
    },
};

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

courier send message \
  --api-key "$COURIER_API_KEY" \
  --message.to '{"email": "sarah@acme-corp.com"}' \
  --message.template nt_01kx4h2jdafq8bk9aftxak4b40 \
  --message.channels '{"email":{"override":{"subject":"Your order has shipped","reply_to":"support@acme-corp.com"}}}'

With Courier MCP, send my nt_01kx4h2jdafq8bk9aftxak4b40 template to sarah@acme-corp.com and override the email subject to "Your order has shipped".

Brand override

The channels.email.override.brand property uses the same schema as the request payload. You can override:

logo
top bar color
brand colors

Example:

{
  "message": {
    // ...rest of request
    "channels": {
      "email": {
        "override": {
          "brand": {
            "settings": {
              "email": {
                "header": {
                  "logo": {
                    "image": "https://www.courier.com/logo.png",
                    "href": "https://www.courier.com"
                  },
                  "barColor": "#674ea7"
                }
              }
            }
          }
        }
      }
    }
  }
}

Allowlist for AWS IP addresses

Some providers, such as Mailgun, let you allowlist the IP addresses that reach their API. Courier runs on AWS and does not publish an IP range to allowlist. Instead, subscribe to the AmazonIpSpaceChanged topic to get notified when AWS IP ranges change. See the AWS documentation.

Get started

Available integrations

Email providers

Available providers

Amazon SES

SendGrid

Postmark

Mailgun

Resend

SMTP

Mandrill

SparkPost

Mailjet

MailerSend

Amply

Gmail

OneSignal

Profile requirements

Send to a recipient

Channel overrides

Available channel override fields

Brand override

Allowlist for AWS IP addresses

​Available providers

Amazon SES

SendGrid

Postmark

Mailgun

Resend

SMTP

Mandrill

SparkPost

Mailjet

MailerSend

Amply

Gmail

OneSignal

​Profile requirements

​Send to a recipient

​Channel overrides

​Available channel override fields

​Brand override

​Allowlist for AWS IP addresses

Available providers

Profile requirements

Send to a recipient

Channel overrides

Available channel override fields

Brand override

Allowlist for AWS IP addresses