Currently, Mailgun dispatches queued messages as fast as receiving ESPs and account-level API quotas allow. There is no native configuration to intentionally throttle sending throughput for a specific sending domain.

To avoid triggering spam filters on newly authenticated domains or to comply with internal system constraints, senders are currently forced to build and manage custom queue workers (e.g., SQS, Google Cloud Tasks) or compute offset timestamps using o:deliverytime for every single recipient.

Proposed Solution: Introduce a Domain Throttling / Rate Limiting setting with the following capabilities:

Configurable Rate Caps: Allow administrators to set limits such as:

• Maximum messages per second/minute/hour (e.g., 50 msgs/minute).
• Ingestion vs. Egress Separation: The Messages API accepts submissions immediately (returning standard HTTP 200/queued responses), while Mailgun's internal domain dispatcher meters the outbound delivery to stay below the configured cap.

Key Use Cases:

• Domain & Subdomain Warmup: Safely ramp up volume on newly registered domains or shared IPs without having to purchase dedicated IPs or manage manual batching schedules.
• Third-Party Integrations: Enables CRMs, e-commerce platforms, and webhook triggers to submit high-volume batches directly to Mailgun without overwhelming downstream inbox providers or sender reputation.
• Reduced Architecture Overhead: Eliminates the need for small-to-midsize engineering teams to maintain external queuing infrastructure solely for outbound pacing.