Twilio SendGrid API

PUBLISHED PROVIDER LIMITS

Limits keep their provider-specific dimensions.

SendGrid publishes distinct limits for individual Web API endpoints and returns endpoint-specific allowance headers.

Authentication: API key

Primary scope: Account And Endpoint

Measured dimensions: Requests, Recipients Per Request

Profile coverage: Published Mail Send throughput and recipient limits, Email Activity and Email Address Validation rates, common Web API rate-limit headers, and 429 handling. Other endpoint-specific limits remain outside this profile.

RESPONSE METADATA

Headers expose the applicable limit state.

X-RateLimit-LimitFormat: Integer

Maximum requests allowed for the endpoint in its active window.

X-RateLimit-RemainingFormat: Integer

Requests remaining for the endpoint in its active window.

X-RateLimit-ResetFormat: Unix Epoch Seconds

Unix time when the endpoint allowance resets.

WHEN A LIMIT IS EXCEEDED

Read the response before choosing a delay.

• Rate-limit responses can use HTTP 429.
• Primary exhaustion signal: X-RateLimit-Remaining reaches zero for the endpoint.

RECOMMENDED HANDLING

Protect both the provider and your own queue.

• Read the rate-limit headers returned by each endpoint.
• Wait until X-RateLimit-Reset before retrying a depleted endpoint window.
• Plan each endpoint independently instead of applying the Mail Send rate globally.

VERIFICATION RECORD

Official sources reviewed