Quality rating is High, Medium, or Low. New numbers start at Medium. Each user block, report-as-spam, or 'mute' contributes negatively. Sending too many marketing messages to non-engaged users degrades it fast.
Low rating means: Meta restricts your daily messaging tier (initial 1K/24hr drops to 250 or fewer), template approvals slow, and continued low rating risks number suspension.
Recovery from Low: pause marketing broadcasts for 7-14 days, send only service messages, ensure new contacts have explicit opt-in, monitor block rate. Most numbers recover within 30 days.