How does the auto-refill threshold work?

The threshold is the single most important number in your auto-refill setup. It is the credit-balance level that decides when a top-up fires. Set it to 2,000 and Valid Email Checker will schedule a refill the moment your combined Monthly plus Pay-As-You-Go balance falls to or below 2,000 credits. Set it to 5,000 and the refill fires earlier — giving you a bigger safety cushion before you hit zero.

How the check actually runs

A background job (monitor-auto-refill) wakes up every minute, fetches the list of users who have auto-refill enabled, and compares each account total balance to that account threshold. If the balance is at or below the threshold, the user is queued for a refill. The actual purchase then fires according to the timing mode you picked — immediately for Aggressive, after a 5-minute delay for Balanced, or at the scheduled time for Scheduled. See which timing mode should I choose for the difference.

Allowed range and default

• Minimum threshold: 1,000 credits
• Maximum threshold: 10,000 credits
• Default: 2,000 credits
• Granularity: 500-credit steps (1,000, 1,500, 2,000, 2,500, and so on)

The lower bound stops users from setting something so low that the refill never has time to complete before the balance hits zero — payment processing and crediting takes a few seconds even on Aggressive timing, and burning through 500 credits in those few seconds is easy on a busy API integration. The upper bound stops users from firing refills constantly on a balance that is barely dented.

How to pick a sensible value

Rule of thumb: pick a threshold that gives you at least one full day of usage as a buffer. If you run a steady 1,500 verifications per day, a threshold around 2,500 leaves you a day of headroom even if the refill itself is briefly delayed. If you run bursty API traffic with peaks of 10,000 verifications in an hour, push the threshold higher — 5,000 or 6,000 — so the bursts cannot drain you below zero between the check tick and the refill landing.

Does the threshold count Monthly or PAYG separately?

No. The check looks at your total balance across both buckets together. If you have 4,000 Monthly credits plus 1,500 PAYG credits and your threshold is 5,000, the check sees 5,500 and does not fire. The moment that total drops to 5,000 or below, auto-refill triggers and the new credits land in your PAYG bucket (which never expires). For the full breakdown of how the two buckets interact, see the credit system explainer.