Limits | API reference | Inbox Triage

Sync window

iCloud, IMAP, and Microsoft keep the newest ~300 messages per selected folder. Gmail syncs ~40 per label each time and fills in to ~300 over its first syncs.
Default folders are Inbox, Sent, and Drafts. Spam and Trash are never synced or searched.
Loading older mail stops at 1000 messages per folder.
A sync that finished less than a minute ago is skipped. Syncing in a loop gains nothing.

/api: 120 requests per minute per API key. /mcp: 300 requests per minute per API key or connected agent.
Short bursts are fine. Each credential can send up to a minute's worth at once, then one more as each share of the minute passes.
Requests with no credential, and credentials that fail, are limited by client address at the same rate.
Over the limit you get 429 with Retry-After in seconds. On /api the body is rate_limited in the usual error shape. On /mcp it is a JSON-RPC error.
Sign-in and OAuth endpoints allow 60 requests per minute per client address.
Providers have their own quotas, and Gmail may slow a sync down.