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Use when a user wants to send one or many emails through Sendmux, choose HTTP versus SMTP, add idempotency or attachments, or use MCP, CLI, SDK, or direct HTTP for outbound email.
默认使用会先检查来源的 Prompt；你也可以切换为直接命令，或下载本地副本。
决定是否安装前，请先阅读 SKILL.md，以及 SkillsMP 当前展示的配套文件。
用 Codex 或 Claude 帮你安装 复制这段 Prompt，粘贴到 Codex、Claude 或其他助手里，让它检查 Skill 页面并帮你完成安装。
直接命令不会经过审查 Prompt；运行前请先检查来源。
npx skills add https://github.com/Sendmux/skills --skill sendmux-send-email命令会保持在同一行。复制前请横向滚动并检查完整内容。
想先保存到本地？可下载 SkillsMP 当前能够提供的文件。
正在显示 SKILL.md
| name | sendmux-send-email |
| description | Use when a user wants to send one or many emails through Sendmux, choose HTTP versus SMTP, add idempotency or attachments, or use MCP, CLI, SDK, or direct HTTP for outbound email. |
| license | Apache-2.0 |
| metadata | {"author":"sendmux","version":"1.0"} |
Use this skill when the user is ready to send outbound email through Sendmux or needs code/commands for sending.
smx_mbx_ key or owner-approved Sending-resource smx_agent_ token for the Sending API.email.send token automatically.| User task | Efficient default |
|---|
| One outbound email | POST /emails/send, MCP sending_send_email, CLI sending:send, or SDK sendingSendEmail. |
| More than one independent outbound email | Batch by default: POST /emails/send/batch, MCP sending_send_email_batch, CLI sending:send:batch, or SDK sendingSendEmailBatch. |
| Sending API attachment file | Upload first with sending_upload_attachment, sending_create_attachment_upload, CLI --attach, or SDK file helpers; send by attachment_id. |
| Replying while working inside one mailbox | Use mailbox send from sendmux-mailbox-agent when the workflow is mailbox-centred. |
| Existing app only supports SMTP | Use SMTP only because the existing tool requires it. For new agent or app integrations, prefer the HTTP Sending API. |
Batch sends accept up to 100 messages. A batch response can partially succeed, so inspect every result item.
Single send body:
{
"from": { "email": "sender@example.com", "name": "Sender Name" },
"to": { "email": "recipient@example.com", "name": "Recipient Name" },
"subject": "Subject line",
"html_body": "<p>Hello.</p>",
"text_body": "Hello."
}
Required fields: from, to, subject, html_body.
Useful optional fields:
text_body: plain text alternative.cc, bcc: arrays of recipients, max 100 each.reply_to: one address object.return_path: envelope sender for bounce handling.custom_headers: custom X-* headers.attachments: up to 10 items. Prefer uploaded refs { "attachment_id": "att_..." }. Inline compatibility form uses filename plus base64 content, optional type, and encoding: "base64".For real local files, do not ask the model to produce base64. Route attachment-heavy work to sendmux-attachments; use CLI --attach, SDK file helpers, sending_upload_attachment, or delegated sending_create_attachment_upload, then pass attachment_id refs. Sending uploads cap each file at 18 MiB and the final sent message at 25 MB. Mailbox blob_id refs are for mailbox sends, not Sending API sends.
Batch send body:
{
"messages": [
{
"from": { "email": "sender@example.com" },
"to": { "email": "alice@example.com" },
"subject": "Hello Alice",
"html_body": "<p>Hi Alice.</p>"
},
{
"from": { "email": "sender@example.com" },
"to": { "email": "bob@example.com" },
"subject": "Hello Bob",
"html_body": "<p>Hi Bob.</p>"
}
]
}
Add Idempotency-Key to every send that may be retried. Use one stable key per logical email or batch.
409 idempotency_conflict.Use MCP when the user's agent already has the Sending server connected:
sending_send_email.sending_send_email_batch.sending_upload_attachment with file_path.sending_create_attachment_upload, then PUT bytes to the returned URL with the returned headers and no Sendmux API key.sending_get_attachment.Include an idempotency key when the client exposes the header parameter. If the MCP client does not expose headers clearly, use CLI, SDK, or direct HTTP for retry-sensitive sends. For attachments through MCP, use sendmux-attachments so the agent chooses file_path, presigned upload, or tiny inline base64 correctly.
For a self-registered agent, use its profile instead of copying credentials:
sendmux sending:send \
--profile my-agent \
--idempotency-key "$IDEMPOTENCY_KEY" \
--body-file ./sendmux-email.json \
--json
The owner must already have accepted the invitation and approved sending. The CLI obtains and caches the short-lived delegated token; the durable read credential is not used directly by the Sending API.
One email:
SENDMUX_API_KEY="$SENDMUX_MBX_KEY" sendmux sending:send \
--idempotency-key "$IDEMPOTENCY_KEY" \
--body '{
"from": { "email": "sender@example.com", "name": "Sender Name" },
"to": { "email": "recipient@example.com", "name": "Recipient Name" },
"subject": "Subject line",
"html_body": "<p>Hello.</p>",
"text_body": "Hello."
}' \
--json
Batch:
SENDMUX_API_KEY="$SENDMUX_MBX_KEY" sendmux sending:send:batch \
--idempotency-key "$IDEMPOTENCY_KEY" \
--body-file ./sendmux-batch.json \
--json
Use --attach ./file.pdf for local files; the CLI uploads bytes first and injects attachment_id refs before sending. Use --body-file for larger JSON payloads or already-prepared Sending API attachment objects.
One email:
import { createSendingClient, sendingSendEmail } from "@sendmux/sending";
const client = createSendingClient({ apiKey: process.env.SENDMUX_API_KEY! });
const response = await sendingSendEmail({
client,
headers: { "Idempotency-Key": idempotencyKey },
body: {
from: { email: "sender@example.com", name: "Sender Name" },
to: { email: "recipient@example.com", name: "Recipient Name" },
subject: "Subject line",
html_body: "<p>Hello.</p>",
text_body: "Hello.",
},
});
console.log(response.data.message_id, response.data.status);
Batch:
import { createSendingClient, sendingSendEmailBatch } from "@sendmux/sending";
const client = createSendingClient({ apiKey: process.env.SENDMUX_API_KEY! });
const response = await sendingSendEmailBatch({
client,
headers: { "Idempotency-Key": idempotencyKey },
body: {
messages,
},
});
for (const result of response.data.results) {
console.log(result.index, result.status, result.message_id, result.error);
}
Use direct HTTP only when MCP, CLI, or SDK is unavailable:
curl -X POST https://smtp.sendmux.ai/api/v1/emails/send \
-H "Authorization: Bearer $SENDMUX_MBX_KEY" \
-H "Content-Type: application/json" \
-H "Idempotency-Key: $IDEMPOTENCY_KEY" \
-d @sendmux-email.json
Single send success returns a 200 success envelope with:
data.message_id: eml_...data.status: queuedBatch success returns a 200 success envelope with:
data.summary.totaldata.summary.queueddata.summary.faileddata.results[] containing index, status, message_id, and optional errorHandle these errors deliberately:
401: missing, invalid, or revoked key.402: insufficient credits.403: key lacks email.send, is not allowed for the sender, or uses the wrong surface.409: idempotency conflict.413: request body exceeds 25 MB.422: validation failed; read error.errors.429 or 503: retry according to response headers.sendmux-getting-started.sendmux-attachments.sendmux-mailbox-agent.sendmux-cli.sendmux-token-efficient-usage.