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Changelog

New Feature: Custom Headers Support​

Date: 2026-06-18

  • Added support for custom headers in both Send Transactional and Send Marketing Email APIs.
  • You can include a headers field in your request body to attach key-value metadata to outgoing emails.
  • Enables scenarios such as preventing Gmail from grouping unrelated emails into the same thread, adding one-click unsubscribe shortcuts, or passing internal tracking references (campaign or order IDs).
  • Added support for email threading via inReplyTo and references to tie outbound emails to existing recipient conversations.

New Feature: Schedule Email​

Date: 2026-06-10

  • Schedule emails for future delivery directly through the Email Gateway API by passing a scheduledAt timestamp in ISO 8601 format, for example 2026-06-10T15:30:00+02:00.
  • Emails can be scheduled up to 72 hours in advance.
  • The API responds immediately with 202 Accepted.
  • Webhook events:
    • Scheduled: fired once the email is confirmed as queued for delivery at the scheduled time.
    • Cancelled: fired once a scheduled email is cancelled. It includes the original scheduled time and the cancellation time.
  • Message Logs: the Email Logs page displays a Scheduled status, which transitions to Delivered once sent.

See Scheduling Emails.

Update: Added Support for .p12 and .pfx File Attachments​

Date: 2026-06-10

  • Allows sending .p12 and .pfx certificate files as email attachments for distributing digital certificates or signing credentials.
  • Attachment format:
    • contentType: application/x-pkcs12
    • content: Base64 encoded file content
    • fileName: filename with a .p12 or .pfx extension

New Feature: SDK Documentation Sidebar​

Date: 2026-06-10

  • Embedded sidebar showing integration code snippets across multiple languages: .NET, Go, Python and Rust.
  • Includes webhook verification and email gateway API examples.
  • Includes one-click copy to clipboard and direct links to documentation.

Improvement: Improved Design for Managing Domains​

Date: 2026-04-01

  • Redesigned domain management overview for faster navigation and issue identification.
  • Streamlined domain onboarding flow with fewer steps and clicks.

Update: Tracking Settings Moved to Domain Level​

Date: 2026-04-01

  • Open and click tracking settings moved from the account level down to the individual sending domain level.
  • Allows independent configuration per domain, for example click tracking enabled on one domain and disabled on another.
  • Existing account-level settings were automatically migrated.

Update: One-Click Unsubscribe Added to Transactional Emails​

Date: 2026-03-01

  • Extended the List-Unsubscribe one-click header to transactional emails. Previously it applied to marketing emails only.
  • Automated unsubscribe processing directly from inbox interfaces to meet stricter mailbox provider requirements and protect deliverability and reputation.

New Feature: Webhook Logs​

Date: 2025-12-01

  • Full log of all webhooks sent to customer endpoints, showing delivery statuses.
  • Ability to inspect webhook payloads and manually retry failed deliveries directly from the UI.

Improvement: New Event Types Added​

Date: 2025-11-01

  • Added three new real-time webhook event types, also available in Integration Mode:
    • sent: triggered when the email is delivered to the recipient's mail server.
    • suppressed: triggered when the address is added to the suppression list.
    • failed: triggered when the email fails to send due to an error.

See Event Types.

Breaking Change: Webhook and Event Type Formatting Update​

Date: 2025-11-01

  • Shifted all webhook response payload properties and event types from PascalCase to camelCase, for example MessageId → messageId, CreatedAt → createdAt, Type: "Bounced" → type: "bounced".

New Feature: IP Whitelisting for API requests​

Date: 2025-10-01

  • Security feature enabling account allow-listing of specific IPv4 addresses or CIDR ranges under Settings > Safeguard.
  • Any API requests from unlisted IPs are automatically rejected.