As an additional security measure for webhooks batch POSTs, you may wish to include custom headers so that batches can be securely sent to your webhook endpoint(s). This gives you the option of rejecting webhook batches if these custom headers and associated values are not included in the batch. The SparkPost webhooks API supports setting…

Using unsubscribe reports to link unsubscribe, list unsubscribe and example implementations through creating and updating an existing Webhook using the API.

A suppression list — or exclusion list — is a list of recipient email addresses to which you do NOT want to send email. Learn more.

This user guide walks you through the steps of uploading and storing a recipient list as CSV file when you are using SparkPost to send email.

Definition and solutions for when you receive a 550 5.7.1 Unconfigured Sending Domain error message as a response when sending a transmission.

This Transmission Best Practices guide covers sending transmissions and monitoring the results for errors. It is intended for a technical audience.

This guide introduces SparkPost's subaccount functionality, which will allow administrators to support separate business units, mailstreams, or customers.

How to set up unsubscribe links: Step-by-step guide to implementing link unsubscribe and list unsubscribe events in SparkPost

SparkPost has added support for sending attachments using the Transmissions API. Attachments can be any file type or inline images.