Download a message attachment. Returns base64 content.
AI agents call mailosaur_files_get_attachment to retrieve information from Mailosaur MCP without modifying anything — typically the context-gathering step in research, monitoring, and reporting workflows, before the agent takes action elsewhere.
This tool retrieves file attachments from messages in a read-only manner. There are no side effects—it merely fetches and returns existing data in base64 format. The operation is non-destructive and non-reversible changes are not made. Severity is low because downloading test email attachments in a Mailosaur testing environment poses minimal risk even if misused by an AI agent.
From the tool's definition Tool name includes 'get' and description states 'Download a message attachment. Returns base64 content.' Downloads and retrieves data without modifying or deleting anything.
Attacks that exploit this kind of access
Download a message attachment. Returns base64 content. It is categorised as a Read tool in the Mailosaur MCP MCP Server, which means it retrieves data without modifying state.
Register the Mailosaur MCP server in PolicyLayer and add a rule for mailosaur_files_get_attachment: 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 Mailosaur MCP. Nothing to install.
mailosaur_files_get_attachment is a Read tool with low risk. Read-only tools are generally safe to allow by default.
Yes. Add a rate_limit block to the mailosaur_files_get_attachment 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 mailosaur_files_get_attachment. 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.
mailosaur_files_get_attachment is provided by the Mailosaur MCP server (mrnewdelhi/mailosaur-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Every MCP server has a record like this.
Type a name, get the same breakdown: verified identity, auth posture, risk grade, capabilities, recommended policy.
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