A limit on how many leads a recipient will accept in a period, used to respect advertiser quotas and protect quality.
A cap is a numeric ceiling on lead volume for a recipient (an advertiser, campaign or offer) over a period — commonly per day or per hour. Advertisers set caps to match the capacity of their sales or call-centre operations; affiliates honour them to keep relationships and payouts stable.
When a recipient's cap is filled, a routing engine either fails over to the next recipient in priority order or parks incoming leads rather than overspending the quota. Caps are usually paired with a schedule (working hours) so leads arrive when the advertiser can process them.
In d0pe caps are enforced atomically per recipient at routing time, with fallback to sibling recipients when one is full.