Zoho ZeptoMail

Use the ZeptoMail API via curl to send transactional emails like password resets, OTPs, welcome emails, and order confirmations.

Official docs: https://www.zoho.com/zeptomail/help/api-home.html

When to Use

Use this skill when you need to:

Send transactional emails (password resets, OTPs, confirmations)
Send templated emails with dynamic merge fields
Batch send to multiple recipients (up to 500)
Track email opens and clicks
Send emails with attachments or inline images

Note: ZeptoMail is for transactional emails only. For marketing/bulk emails, use Zoho Campaigns instead.

Prerequisites

Sign up at Zoho ZeptoMail
Add and verify your domain
Create a Mail Agent and get your Send Mail Token

Get API Token

Go to Mail Agents in ZeptoMail dashboard
Click on your Mail Agent
Go to SMTP & API tab
Copy the Send Mail Token

export ZEPTOMAIL_API_KEY="your-send-mail-token"

Pricing

Free tier: 10,000 emails
Paid: $2.50 per 10,000 emails

How to Use

Base URL: https://api.zeptomail.com/v1.1

1. Send Basic Email

Write to /tmp/zeptomail_request.json:

{
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "to": [
    {
      "email_address": {
        "address": "user@example.com",
        "name": "User"
      }
    }
  ],
  "subject": "Welcome to Our Service",
  "htmlbody": "<h1>Welcome!</h1><p>Thank you for signing up.</p>"
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

2. Send Plain Text Email

Write to /tmp/zeptomail_request.json:

{
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "to": [
    {
      "email_address": {
        "address": "user@example.com",
        "name": "User"
      }
    }
  ],
  "subject": "Your OTP Code",
  "textbody": "Your one-time password is: 123456\n\nThis code expires in 10 minutes."
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

3. Send Email with Tracking

Enable open and click tracking:

Write to /tmp/zeptomail_request.json:

{
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "to": [
    {
      "email_address": {
        "address": "user@example.com",
        "name": "User"
      }
    }
  ],
  "subject": "Order Confirmation #12345",
  "htmlbody": "<p>Your order has been confirmed. <a href=\"https://example.com/track\">Track your order</a></p>",
  "track_clicks": true,
  "track_opens": true,
  "client_reference": "order-12345"
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

4. Send to Multiple Recipients (CC/BCC)

Write to /tmp/zeptomail_request.json:

{
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "to": [
    {
      "email_address": {
        "address": "user1@example.com",
        "name": "User 1"
      }
    }
  ],
  "cc": [
    {
      "email_address": {
        "address": "user2@example.com",
        "name": "User 2"
      }
    }
  ],
  "bcc": [
    {
      "email_address": {
        "address": "admin@example.com",
        "name": "Admin"
      }
    }
  ],
  "subject": "Team Update",
  "htmlbody": "<p>Here is the latest update for the team.</p>",
  "reply_to": [
    {
      "address": "support@yourdomain.com",
      "name": "Support"
    }
  ]
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

5. Send Email with Attachment (Base64)

# Encode file to base64
FILE_CONTENT=$(base64 -i /path/to/file.pdf)

Write to /tmp/zeptomail_request.json:

{
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "to": [
    {
      "email_address": {
        "address": "user@example.com",
        "name": "User"
      }
    }
  ],
  "subject": "Your Invoice",
  "htmlbody": "<p>Please find your invoice attached.</p>",
  "attachments": [
    {
      "name": "invoice.pdf",
      "mime_type": "application/pdf",
      "content": "${FILE_CONTENT}"
    }
  ]
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

6. Send Email with Inline Image

# Encode image to base64
IMAGE_CONTENT=$(base64 -i /path/to/logo.png)

Write to /tmp/zeptomail_request.json:

{
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "to": [
    {
      "email_address": {
        "address": "user@example.com",
        "name": "User"
      }
    }
  ],
  "subject": "Newsletter",
  "htmlbody": "<p><img src='cid:logo'/></p><p>Welcome to our newsletter!</p>",
  "inline_images": [
    {
      "cid": "logo",
      "name": "logo.png",
      "mime_type": "image/png",
      "content": "${IMAGE_CONTENT}"
    }
  ]
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

7. Send Templated Email

Use pre-defined templates with merge fields:

Write to /tmp/zeptomail_request.json:

{
  "template_key": "your-template-key",
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "to": [
    {
      "email_address": {
        "address": "user@example.com",
        "name": "User"
      }
    }
  ],
  "merge_info": {
    "user_name": "John",
    "order_id": "12345",
    "total": "$99.00"
  }
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email/template" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

Template example (in ZeptoMail dashboard):

<p>Hi {{user_name}},</p>
<p>Your order #{{order_id}} totaling {{total}} has been shipped!</p>

8. Batch Send (Multiple Recipients)

Send to up to 500 recipients with personalized merge fields:

Write to /tmp/zeptomail_request.json:

{
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "subject": "Your Monthly Report - {{month}}",
  "htmlbody": "<p>Hi {{name}},</p><p>Here is your report for {{month}}.</p>",
  "to": [
    {
      "email_address": {
        "address": "user1@example.com",
        "name": "User 1"
      },
      "merge_info": {
        "name": "Alice",
        "month": "December"
      }
    },
    {
      "email_address": {
        "address": "user2@example.com",
        "name": "User 2"
      },
      "merge_info": {
        "name": "Bob",
        "month": "December"
      }
    }
  ]
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email/batch" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

9. Batch Send with Template

Write to /tmp/zeptomail_request.json:

{
  "template_key": "your-template-key",
  "from": {
    "address": "noreply@yourdomain.com",
    "name": "Your App"
  },
  "to": [
    {
      "email_address": {
        "address": "user1@example.com",
        "name": "User 1"
      },
      "merge_info": {
        "user_name": "Alice",
        "code": "ABC123"
      }
    },
    {
      "email_address": {
        "address": "user2@example.com",
        "name": "User 2"
      },
      "merge_info": {
        "user_name": "Bob",
        "code": "XYZ789"
      }
    }
  ]
}

Then run:

curl -s "https://api.zeptomail.com/v1.1/email/template/batch" -X POST --header "Authorization: Zoho-enczapikey $(printenv ZEPTOMAIL_API_KEY)" --header "Content-Type: application/json" -d @/tmp/zeptomail_request.json

Response Format

Success Response

{
  "data": [
  {
  "code": "EM_104",
  "additional_info": [],
  "message": "OK"
  }
  ],
  "message": "OK",
  "request_id": "abc123..."
}

Error Response

{
  "error": {
  "code": "TM_102",
  "details": [
  {
  "code": "TM_102",
  "message": "Invalid email address",
  "target": "to"
  }
  ],
  "message": "Invalid request"
  },
  "request_id": "abc123..."
}

Common Error Codes

Code	Description
TM_101	Authentication failed (invalid token)
TM_102	Invalid request parameters
TM_103	Domain not verified
TM_104	Rate limit exceeded
EM_104	Success

Guidelines

Transactional only - Do not use for marketing or bulk promotional emails
Verify domain first - Sender address must be from a verified domain
Size limit - Total email size (headers + body + attachments) must not exceed 15 MB
Batch limit - Maximum 500 recipients per batch request
Use templates - For consistent emails, create templates in the dashboard
Track reference - Use client_reference to correlate emails with your transactions
TLS required - API only supports TLS v1.2+

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Zoho ZeptoMail

When to Use

Prerequisites

Get API Token

Pricing

How to Use

1. Send Basic Email

2. Send Plain Text Email

3. Send Email with Tracking

4. Send to Multiple Recipients (CC/BCC)

5. Send Email with Attachment (Base64)

6. Send Email with Inline Image

7. Send Templated Email

8. Batch Send (Multiple Recipients)

9. Batch Send with Template

Response Format

Success Response

Error Response

Common Error Codes

Guidelines

Source Transparency

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