Refresh the local SQLite cache from IMAP. Synchronous; can take 5-30s for first sync. Subsequent runs are incremental.
AI agents use sync_force to create or update resources in MCP Email Service — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your MCP Email Service environment.
This tool pulls data from IMAP and writes/updates a local SQLite cache. It modifies local state (the cache database) but does not delete or irreversibly destroy data. The primary action is a cache refresh/update, placing it in Write. Severity is medium because a forced sync could overwrite local cache state or trigger unintended side effects at scale, but it is generally reversible.
From the tool's definition Refresh the local SQLite cache from IMAP... Subsequent runs are incremental
Documented attack patterns abuse exactly the kind of access sync_force gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and MCP Email Service, and nothing reaches the server without passing your rules. This is the rule we recommend for sync_force:
{
"version": "1",
"default": "deny",
"tools": {
"sync_force": {
"limits": [
{
"counter": "sync_force_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}sync_force stays usable, but capped — an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.
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Refresh the local SQLite cache from IMAP. Synchronous; can take 5-30s for first sync. Subsequent runs are incremental. It is categorised as a Write tool in the MCP Email Service MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the MCP Email Service MCP server in PolicyLayer and add a rule for sync_force: 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 MCP Email Service. Nothing to install.
sync_force 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 sync_force 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 sync_force. 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.
sync_force is provided by the MCP Email Service MCP server (leeguooooo/mailbox). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from MCP Email Service, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
Free to start. No card required.
16 MCP Email Service tools catalogued and risk-classified — across an index of 43,000+ MCP servers.