The Agent Skills Directory

[COMMAND_EXECUTION]: The skill instructions direct the agent to compile a local binary using go build and subsequently execute it. This involves running code with the user's local permissions.
[EXTERNAL_DOWNLOADS]: The skill references dependencies from the emersion organization's GitHub repositories (github.com/emersion/go-smtp and github.com/emersion/go-imap/v2) which are fetched during the build process. These are well-known libraries in the Go community.
[DATA_EXFILTRATION]: The tool is designed to handle sensitive credentials via the -user and -pass flags. These credentials are transmitted to the specified remote host during authentication tests.
[PROMPT_INJECTION]: The skill has an indirect prompt injection surface because it ingests and processes data from external SMTP/IMAP servers and presents that data to the agent.
Ingestion points: Terminal output from the ./mailtester binary, which includes server greetings, capability strings, and mailbox metadata fetched from remote hosts.
Boundary markers: None present; the agent processes the raw output of the diagnostic tool.
Capability inventory: The skill can execute a local binary and perform network operations to arbitrary hosts and ports.
Sanitization: There is no evidence of sanitization or filtering of the content received from remote servers before it is processed by the agent.

mailtester