{
  "envelopes": [
  {
    "to": {"name":"宛先", "address": "to@example.net"},
    "cc": [{"name":"CC宛先", "address": "cc@example.net"}],
    "bcc": [{"name":"BCC宛先", "address": "bcc@example.net"}],
    "subject": "個別サブジェクト",
    "headers": {
      "x-sample": "overwrite-root-headers-value"
    },
    "replace_value": {
      "#REPLACE#": "こちらが優先して置換されます",
      "#SUBJECT#": "こちらが優先して置換されます",
      "#FROM#": "こちらが優先して置換されます",
      "#REPLY-TO#": "こちらが優先して置換されます"
    },
    "custom_args": {
      "user_id": "00001"
    },
    "tracking": {
      "query": {
        "user_id": "1234",
        "email": "to@example.net"
      }
    }
  }
],
  "from": {"address": "from@exmaple.net", "name": "差出人 #FROM#"},
  "reply_to": {"address": "reply@example.net", "name": "返信先 #REPLY-TO#"},
  "subject": "サンプルメール #SUBJECT#",
  "body": {
    "text": "これはテキストパートです\n#REPLACE#",
    "html": "<p>これは<strong>HTML</strong>パートです<br/>#REPLACE#<br/><img src=\"cid:dot@example.net\"/></p>"
  },
  "attachment": [
    {
      "content": "R0lGODlhAQABAIAAAAUEBAAAACwAAAAAAQABAAACAkQBADs=",
      "name": "ドット.gif",
      "type": "image/gif",
      "dispostion": "inline",
      "content_id": "dot@example.net"
    }
  ],
  "custom_args": {
    "user_id": "00000"
  },
  "headers": {
    "x-sample": "sample"
  },
  "replace_value": {
    "#REPLACE#": "置換されます",
    "#SUBJECT#": "Subjectが置換されます",
    "#FROM#": "Fromが置換されます",
    "#REPLY-TO#": "Reply-Toが置換されます"
  },
  "timestamp": 1514732400,
  "batch_id": "IDA001",
  "tracking": {
    "tracking": "may",
    "beacon": true,
    "expires": [
      {
        "url":"https://example.com",
        "timestamp": 1546182000,
        "redirect": "https://example.org"
      }
    ],
    "custom_domain": "click.mydomain.org",
    "relay": {"r":"https://example.jp"}
  },
  "dkim": {
    "selector": "myselector"
  }
} 

{"code":200}

{"code":400,"error":"validation error", "validation_errors":"subject required"}

{
  ...
  "from": {"address":"from@example.com"}
  "subject":"root subject",
  "headers":{"x-header":"root"},
  "custom_args":{"arg1":"root"},
  "replace_value":{"#R#","root"},
  "envelopes": [
    {
      "to": {"address":"to@example.com"},
      "subject":"envelope subject #R#",
      "headers":{"X-HEADER":"envelope"},
      "custom_args":{"arg1","envelope"},
      "replace_value":{"#R#","envelope"}
    }
  ],
  "body":{"text":"body #R#"},
  ...
}

メールヘッダ:
From: <from@example.com>
To: <to@example.com>
Subject: envelope subject envelope
X-HEADER: envelope

メール本文:
body envelope

{
  "mta_mail_id":"9999999999",
  "email":"to@example.com",
  "timestamp":1507785394,
  "custom_args":{"arg1":"envelope"},
  "event":"Delivered",
  "batch_id":"sample."
}

...
"replace_value":{"#REPLACE0#":"これはrootの0です","#REPLACE1#":"これはrootの1です"},
"from":{"address":"from@example.com":"name":"#REPLACE1#"},
"reply_to":{"address":"reply@example.com":"name":"#REPLACE0#"},
"body":{"text":"#REPLACE0#,#REPLACE1#,#REPLACE2#"},
"subject":"#REPLACE2#",
"envelopes":[
  {
    "to":{"address":"to@example.com"},
    "replace_value":{"#REPLACE1":"これはenvelopeの1です","#REPLACE2#":"改行前\n改行後"},
    "subject":"#REPLACE1#"
  }
],
...

メールヘッダ:
From: "これはenvelopeの1です" <from@example.com>
To: <to@example.com>
Reply-To: "これはrootの0です" <reply@example.com>
Subject: 改行前 改行後

メール本文:
これはrootの0です,これはenvelopeの1です,改行前
改行後

{
  "subject": "this is minimum request",
  "from": {"address":"from@example.com"},
  "body": {"text": "minimum request body."},
  "envelopes": [
    {"to":{"address":"to@example.com"}}
  ]
}

{
  "subject": "サブジェクト",
  "from": {"address": "from@example.com"},
  "envelopes": [
    {"to": {"address": "to@example.com"}}
  ],
  "headers": {
    "List-Unsubscribe-Post": "List-Unsubscribe=One-Click",
    "List-Unsubscribe": "<https://example.com/r?store_id=1>,<mailto:notify@example.com>"
  },
  "body": {
    "text": "これはテキストパートです",
    "html": "これはHTMLパートです"
  }
} 

From: <from@example.com>
To: <to@example.com>
Subject: サブジェクト
...
DKIM-Signature: ... ; h=From:To:Subject:Message-Id:List-Unsubscribe:List-Unsubscribe-Post; ...
List-Unsubscribe: <https://example.com/r?store_id=1>,<mailto:notify@example.com>
List-Unsubscribe-Post: List-Unsubscribe=One-Click
...