# Mail Send Send emails to one or more recipients. The API processes requests asynchronously and returns a `202` response that includes an `operationId` you can use to track send status. ## Send to a single recipient Send an email to a single recipient: ```bash curl -X POST 'https://comms.twilio.com/v1/Emails' \ -H 'Content-Type: application/json' \ -d '{ "from": { "address": "support@example.com", "name": "Support Team" }, "to": [ { "address": "john.doe@example.com", "name": "John Doe" } ], "content": { "subject": "Your subject line", "html": "

Your message content in HTML format.

", "text": "Your message content in plain text." } }' \ -u $TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN ``` **Response (202 Accepted)**: ```json { "operationId": "comms_operation_01h9krwprkeee8fzqspvwy6nq8", "operationLocation": "https://comms.twilio.com/v1/Emails/Operations/comms_operation_01h9krwprkeee8fzqspvwy6nq8" } ``` ## Send to multiple recipients Send the same email to multiple recipients: ```bash curl -X POST 'https://comms.twilio.com/v1/Emails' \ -H 'Content-Type: application/json' \ -d '{ "from": { "address": "support@example.com", "name": "Support Team" }, "to": [ { "address": "john.doe@example.com", "name": "John Doe" }, { "address": "jane.smith@example.com", "name": "Jane Smith" } ], "content": { "subject": "Your subject line", "html": "

Your message content in HTML format.

", "text": "Your message content in plain text." } }' \ -u $TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN ``` ## Personalization with variables Use Liquid templating to personalize emails for each recipient: ```bash curl -X POST 'https://comms.twilio.com/v1/Emails' \ -H 'Content-Type: application/json' \ -d '{ "from": { "address": "support@example.com", "name": "Support Team" }, "to": [ { "address": "jane.doe@example.com", "variables": { "firstName": "Jane", "lastName": "Doe" } }, { "address": "john.doe@example.com", "variables": { "firstName": "John", "lastName": "Doe" } } ], "content": { "subject": "Hello {{ firstName }}", "html": "Hey {{ firstName | default: '\''there'\'' }} {{ lastName }}, your order is ready.", "text": "Hey {{ firstName | default: '\''there'\'' }} {{ lastName }}, your order is ready." } }' \ -u $TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN ``` ## Schedule an email Schedule an email to be sent at a future time. Provide a `sendAt` value in [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339) format. You can schedule emails up to 7 days in advance. ```bash curl -X POST 'https://comms.twilio.com/v1/Emails' \ -H 'Content-Type: application/json' \ -d '{ "from": { "address": "support@example.com", "name": "Support Team" }, "to": [ { "address": "john.doe@example.com", "name": "John Doe" } ], "content": { "subject": "Scheduled Reminder", "html": "This is your scheduled reminder." }, "schedule": { "sendAt": ["2026-12-15T14:15:22Z"] } }' \ -u $TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN ``` ## Custom headers Add custom headers to your emails for tracking and categorization: ```bash curl -X POST 'https://comms.twilio.com/v1/Emails' \ -H 'Content-Type: application/json' \ -d '{ "from": { "address": "marketing@example.com", "name": "Marketing Team" }, "to": [ { "address": "customer@example.com", "name": "Customer" } ], "content": { "subject": "Special Offer", "html": "

Exclusive Deal!

", "text": "Exclusive Deal!", "headers": { "X-Campaign-ID": "CAMPAIGN-2026-Q1", "X-Customer-Segment": "premium", "X-Priority": "high" } } }' \ -u $TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN ``` **Note**: You can't override these headers: `x-sg-id`, `x-sg-eid`, `received`, `dkim-signature`, `Content-Type`, `Content-Transfer-Encoding`, `To`, `From`, `Subject`, `Reply-To`, `CC`, `BCC`. ## Tags for tracking Add custom metadata tags to emails for filtering and tracking: ```bash curl -X POST 'https://comms.twilio.com/v1/Emails' \ -H 'Content-Type: application/json' \ -d '{ "from": { "address": "newsletter@example.com", "name": "Newsletter Team" }, "to": [ { "address": "john.doe@example.com", "name": "John Doe" } ], "content": { "subject": "January Newsletter", "html": "

Newsletter

" }, "tags": { "campaign": "monthlyNewsletter", "edition": "january_2026" } }' \ -u $TWILIO_ACCOUNT_SID:$TWILIO_AUTH_TOKEN ``` For more details on tag constraints, see [Tags](/docs/email/api/overview#tags).