Agent skill

mailsac

MailSac API for disposable email testing. Use when user mentions "MailSac", "test email", "disposable email", or email testing.

View SKILL.md on GitHub Repository
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Install this agent skill to your Project

npx add-skill https://github.com/vm0-ai/vm0-skills/tree/main/mailsac

SKILL.md

Mailsac

Use the Mailsac API via direct curl calls to manage disposable email addresses for testing and QA automation.

Official docs: https://docs.mailsac.com/

When to Use

Use this skill when you need to:

  • Receive test emails in disposable inboxes
  • Validate email addresses (check format and disposable status)
  • Automate email verification flows in E2E tests
  • Configure webhooks for real-time email notifications
  • Manage private email addresses for testing

Prerequisites

  1. Sign up at https://mailsac.com/
  2. Get your API key from the dashboard (Account > API Key)
bash
export MAILSAC_API_KEY="your-api-key"

How to Use

All examples below assume you have MAILSAC_API_KEY set.

Base URL: https://mailsac.com

1. Messages - Read Emails

Retrieve and read emails from any inbox.

List Messages in Inbox

bash
curl -s "https://mailsac.com/api/addresses/test@mailsac.com/messages" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq .

Read Message Content (Plain Text)

Replace <message-id> with the actual messageId from the list:

bash
curl -s "https://mailsac.com/api/text/test@mailsac.com/<message-id>" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"

Read Message Content (HTML)

bash
curl -s "https://mailsac.com/api/body/test@mailsac.com/<message-id>" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"

Get Raw SMTP Message (with headers and attachments)

bash
curl -s "https://mailsac.com/api/raw/test@mailsac.com/<message-id>" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"

Get Message Headers as JSON

bash
curl -s "https://mailsac.com/api/headers/test@mailsac.com/<message-id>" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq .

Message Format Endpoints:

Endpoint Description
/api/text/{email}/{messageId} Plain text body
/api/body/{email}/{messageId} Sanitized HTML body
/api/dirty/{email}/{messageId} Unsanitized HTML with inlined images
/api/raw/{email}/{messageId} Complete SMTP message
/api/headers/{email}/{messageId} JSON headers

2. Messages - Delete

Delete single messages or purge entire inboxes.

Delete Single Message

bash
curl -s -X DELETE "https://mailsac.com/api/addresses/test@mailsac.com/messages/<message-id>" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"

Purge Entire Inbox (Enhanced Address only)

bash
curl -s -X DELETE "https://mailsac.com/api/addresses/test@mailsac.com/messages" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"

Note: Starred messages will NOT be purged. Unstar them first if you want to delete everything.

Delete All Messages in Custom Domain

bash
curl -s -X PUT "https://mailsac.com/api/domains/yourdomain.com/delete-all-domain-mail" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"

3. Private Addresses - Reserve and Release

Manage private email addresses for exclusive use.

Reserve a Private Address

bash
curl -s -X POST "https://mailsac.com/api/addresses/mytest@mailsac.com" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq .

Response:

json
{
  "_id": "mytest@mailsac.com",
  "owner": "your-username",
  "forward": null,
  "webhook": null,
  "webhookSlack": null,
  "enablews": false,
  "created": "2024-01-01T00:00:00.000Z",
  "updated": "2024-01-01T00:00:00.000Z"
}

List Your Private Addresses

bash
curl -s "https://mailsac.com/api/addresses" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq .

Release a Private Address

bash
curl -s -X DELETE "https://mailsac.com/api/addresses/mytest@mailsac.com" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"

Release Address and Delete All Messages

bash
curl -s -X DELETE "https://mailsac.com/api/addresses/mytest@mailsac.com?deleteAddressMessages=true" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"

4. Webhook Forwarding

Configure webhooks to receive email notifications in real-time.

Set Webhook for Private Address

Write to /tmp/mailsac_webhook.json:

json
{
  "webhook": "https://your-server.com/email-webhook"
}

Then run:

bash
curl -s -X PUT "https://mailsac.com/api/private-address-forwarding/mytest@mailsac.com" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" --header "Content-Type: application/json" -d @/tmp/mailsac_webhook.json | jq .

Remove Webhook

Write to /tmp/mailsac_webhook.json:

json
{
  "webhook": ""
}

Then run:

bash
curl -s -X PUT "https://mailsac.com/api/private-address-forwarding/mytest@mailsac.com" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" --header "Content-Type: application/json" -d @/tmp/mailsac_webhook.json | jq .

Webhook Payload Format:

json
{
  "text": "Email body content",
  "subject": "Email subject",
  "from": [{"address": "sender@example.com", "name": "Sender Name"}],
  "to": [{"address": "recipient@mailsac.com", "name": ""}],
  "headers": {},
  "messageId": "unique-message-id",
  "date": "2024-01-01T00:00:00.000Z",
  "receivedDate": "2024-01-01T00:00:00.000Z",
  "raw": "Full RFC-formatted email"
}

5. Email Validation

Validate email addresses and detect disposable email services.

Validate Single Email

bash
curl -s "https://mailsac.com/api/validations/addresses/test@example.com" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq .

Response:

json
{
  "email": "test@example.com",
  "isValidFormat": true,
  "isDisposable": false,
  "disposableDomains": [],
  "aliases": [],
  "domain": "example.com",
  "local": "test"
}

Check if Email is Disposable

bash
curl -s "https://mailsac.com/api/validations/addresses/test@mailsac.com" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq '{email, isDisposable}'

Validation Response Fields:

Field Description
isValidFormat Email syntax is valid
isDisposable Email is from a disposable service
disposableDomains List of identified disposable domains
aliases Domain aliases and IP addresses
domain Domain part of email
local Local part of email

6. Send Email (Outgoing)

Send emails via API (requires outgoing message credits).

Write to /tmp/mailsac_outgoing.json:

json
{
  "to": "recipient@example.com",
  "from": "sender@mailsac.com",
  "subject": "Test Email",
  "text": "This is the email body content."
}

Then run:

bash
curl -s -X POST "https://mailsac.com/api/outgoing-messages" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" --header "Content-Type: application/json" -d @/tmp/mailsac_outgoing.json | jq .

Note: Sending requires purchased credits unless sending within your custom domain.

7. Attachments

Download attachments from received emails.

Get Attachment by MD5 Hash

bash
curl -s "https://mailsac.com/api/addresses/test@mailsac.com/messages/<message-id>/attachments/<attachment-md5>" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" > attachment.bin

Get Raw Message and Parse Attachments

bash
curl -s "https://mailsac.com/api/raw/test@mailsac.com/<message-id>" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" > message.eml

Note: For public addresses, attachments must be downloaded via API; they are not viewable on the website.

8. Star/Save Messages

Prevent messages from being auto-deleted by starring them.

Star a Message

bash
curl -s -X PUT "https://mailsac.com/api/addresses/test@mailsac.com/messages/<message-id>/star" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq .

Practical Examples

Wait for Email and Extract Verification Code

bash
EMAIL="test-$(date +%s)@mailsac.com"
echo "Use this email for registration: $EMAIL"

# Poll for new message (check every 5 seconds, max 60 seconds)
for i in $(seq 1 12); do
  MESSAGES=$(curl -s "https://mailsac.com/api/addresses/$EMAIL/messages" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)")
  COUNT=$(echo "$MESSAGES" | jq 'length')
  if [ "$COUNT" -gt "0" ]; then
    MESSAGE_ID=$(echo "$MESSAGES" | jq -r '.[0]._id')
    echo "Message received: $MESSAGE_ID"
    curl -s "https://mailsac.com/api/text/$EMAIL/$MESSAGE_ID" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"
    break
  fi
  echo "Waiting for email... ($i/12)"
  sleep 5
done

List Recent Messages with Subject and Sender

bash
curl -s "https://mailsac.com/api/addresses/test@mailsac.com/messages" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq '.[] | {subject, from: .from[0].address, received: .received}'

Clean Up Test Inbox Before Tests

bash
curl -s -X DELETE "https://mailsac.com/api/addresses/test@mailsac.com/messages" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)"
echo "Inbox purged"

Check if Email Service is Disposable

bash
curl -s "https://mailsac.com/api/validations/addresses/user@tempmail.com" --header "Mailsac-Key: $(printenv MAILSAC_API_KEY)" | jq 'if .isDisposable then "DISPOSABLE" else "LEGITIMATE" end'

Response Format

Message List Response

json
[
  {
    "_id": "message-id-here",
    "from": [{"address": "sender@example.com", "name": "Sender"}],
    "to": [{"address": "test@mailsac.com", "name": ""}],
    "subject": "Email Subject",
    "received": "2024-01-01T00:00:00.000Z",
    "size": 1234,
    "attachments": []
  }
]

Validation Response

json
{
  "email": "test@mailsac.com",
  "isValidFormat": true,
  "isDisposable": true,
  "disposableDomains": ["mailsac.com"],
  "aliases": ["104.197.186.12"],
  "domain": "mailsac.com",
  "local": "test"
}

Limits and Quotas

Type Limit
Public address message retention 4 days
Public inbox max messages 6
Max message size 2.5 MB
Operations quota reset 1st of each month (UTC)

Guidelines

  1. Public vs Private: Public addresses are accessible by anyone; use private addresses for sensitive test data
  2. Starred messages: Star important messages to prevent auto-deletion
  3. Rate limits: Free accounts may experience throttling; paid plans have higher limits
  4. Webhook reliability: Check Recent Activity page for webhook debugging
  5. Attachments security: For security reasons, attachments on public addresses require API access
  6. Operations count: Listing messages + reading content = 2 API operations

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