Quota-aware sending across 6 email providers — quota providers first, pay-per-send as overflow
Test sends verify that the provider API is working and the from-domain is authenticated. Use a real email address as the recipient.
Priority Order
Daily Budget Formula
dailyBudget = floor(remainingMonthlyQuota / daysLeftInCycle)The system picks the highest-priority provider that still has daily budget remaining. If all quota providers are exhausted, Mailgun absorbs all overflow.
Automatic failover: if a provider returns an error, the next provider in priority order is tried immediately.