Twilio SendGrid

What you can build

• Backorder notice that knows when it bounced

  The operator proposes a backorder email per affected order. Once approved and sent, a bounce or dropped event on the same custom_args reopens the case so a person can reach the customer another way.

  With Backorder Notice

• Dunning cadence with suppression checks

  Before each reminder, the recipient is checked against /v3/suppression/bounces and /v3/suppression/unsubscribes. A suppressed address stops the cadence and the operator proposes a different channel.

  With Dunning Cadence

• Outage notice on a schedule

  For a planned maintenance window, the operator drafts the notice and proposes a send_at time up to 72 hours ahead with a batch_id. A person approves once; SendGrid holds it until then.

  With Outage Notice

Requirements

• A Twilio SendGrid account and an API key with Mail Send access, plus suppression read access if lists are checked
• A sender address or domain you have authenticated in SendGrid, since from must match one
• An HTTPS endpoint Fibric operates to receive the Event Webhook, configured under Settings > Mail Settings > Webhook Settings or through the Webhooks API
• For GET /v3/messages: the additional email activity history add-on under Account Details > Your Products > Add-ons
• For parent accounts acting for a subuser: the on-behalf-of header with the subuser's username

Authentication

A SendGrid API key with the permissions you assign, created at app.sendgrid.com under Settings > API Keys and sent as Authorization: Bearer on every request.

Limits

• Each endpoint has its own allowance per refresh period; over it the API returns 429, and X-RateLimit-Limit, X-RateLimit-Remaining, and X-RateLimit-Reset say when to retry
• If the webhook endpoint does not answer 2xx, SendGrid retries at increasing intervals for up to 24 hours, then stops
• A send may carry at most 1,000 personalizations, 10 categories, and 10,000 bytes of custom_args
• Suppression list pages return at most 500 records; message search returns at most 1,000 and only with the paid add-on

Questions and answers

How does Fibric know a message bounced?

Two ways. The Event Webhook posts a bounce or dropped event carrying the sg_message_id and any custom_args from the send. GET /v3/suppression/bounces also lists bounced addresses with a reason and an enhanced SMTP status, filterable by start_time, end_time, and email.

How is the Event Webhook secured?

SendGrid offers a Signed Event Webhook and OAuth 2.0, and recommends one or both. Signed posts carry an ECDSA signature in X-Twilio-Email-Event-Webhook-Signature with X-Twilio-Email-Event-Webhook-Timestamp, checked against the raw body. OAuth uses client credentials (Client ID, Client Secret, Token URL) and sends the token in the Authorization header.

Can Fibric look up a single message after the fact?

Only with the Email Activity add-on. GET /v3/messages accepts a query of up to 160 filter conditions and returns up to 1,000 messages. Without the add-on, message-level history has to come from the Event Webhook stream you keep.