Send up to 50 transactional emails in a single call. More efficient than individual sends — includes a 10% batch discount. Pricing (with batch discount): - Plain text: $0.0009 per email - HTML: $0.005 per email Args: - wallet_address (string): Your 0x... wallet address - recipients (array): Up to...
Risk signalsAccepts raw HTML/template content (body) · High parameter count (10 properties)
Part of the MailerAstro server.
Free to start. No card required.
AI agents use mailerastro_send_batch to create or modify resources in MailerAstro. Write operations carry medium risk because an autonomous agent could trigger bulk unintended modifications. Rate limits prevent a single agent session from making hundreds of changes in rapid succession. Argument validation ensures the agent passes expected values.
Without a policy, an AI agent could call mailerastro_send_batch repeatedly, creating or modifying resources faster than any human could review. PolicyLayer's rate limiting ensures write operations happen at a controlled pace, and argument validation catches malformed or unexpected inputs before they reach MailerAstro.
Write tools can modify data. A rate limit prevents runaway bulk operations from AI agents.
{
"version": "1",
"default": "deny",
"tools": {
"mailerastro_send_batch": {
"limits": [
{
"counter": "mailerastro_send_batch_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}See the full MailerAstro policy for all 6 tools.
These attack patterns abuse exactly the kind of access mailerastro_send_batch gives an agent. Each links to the full case and the policy that stops it:
Other write tools across the catalogue. The same approach applies to each: rate-limit and validate the arguments.
Send up to 50 transactional emails in a single call. More efficient than individual sends — includes a 10% batch discount. Pricing (with batch discount): - Plain text: $0.0009 per email - HTML: $0.005 per email Args: - wallet_address (string): Your 0x... wallet address - recipients (array): Up to 50 objects with { email, name? } - from (string): Sender email address - from_name (string, optional): Sender display name - subject (string): Email subject line - body (string): Email body content - content_type ('text' | 'html'): Content format (default: 'text') - reply_to (string, optional): Reply-to address Returns: JSON with: success, totalSent, totalFailed, results (per-recipient), totalCost, remainingBalance Examples: - Notify 20 users: wallet_address="0x...", recipients=[{email: "a@b.com"}, ...], from="alerts@myapp.com", subject="Update", body="New feature launched" Error Handling: - 402: Insufficient balance for entire batch. Partial sends are not performed. - Maximum 50 recipients per batch call.. It is categorised as a Write tool in the MailerAstro MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MailerAstro MCP server in PolicyLayer and add a rule for mailerastro_send_batch: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches MailerAstro. Nothing to install.
mailerastro_send_batch is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the mailerastro_send_batch rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.
Set action: deny in the PolicyLayer policy for mailerastro_send_batch. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.
mailerastro_send_batch is provided by the MailerAstro MCP server (mailerastro/mailerastro-email). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 6 MailerAstro tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
Free to start. No card required.
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