A marketing qualified lead is a lead whose behaviour, such as downloads, webinar attendance, pricing page visits or email engagement, has pushed its score past a threshold that marketing and sales agreed on. It is a handoff signal, not a judgement about budget or authority. MQLs typically convert to customers at 1 to 5%, the lowest rate of the qualified grades, because engagement measures curiosity rather than need.
The threshold is a points total. A pricing page view might score 20, a whitepaper 10, an unsubscribe minus 50. When the total crosses, say, 60, the record becomes an MQL and routes to a sales development rep. The weights come from historical conversion data where it exists and from guesswork where it does not.
The common failure is scoring activity that an unreachable record can still generate. A contact whose work email bounced can keep visiting pages from a saved link. Adding a reachability multiplier, zero for invalid, half for catch-all or unknown, one for confirmed valid, stops dead records reaching sales with a high score. See SaaS lead scoring for a worked model.
A SaaS team generates 400 MQLs a month. Verification at the form shows 8% of inbound addresses are typos or throwaways. Without the check, 32 of those 400 MQLs are handed to sales each month with a confident score and no working channel; with it, the form rejects the typo before the record exists.
Verify a list or a single address. 100 free checks a month, unknowns refunded.
Verify Leads - FreeAyoub built BounceZero's 5-stage validation pipeline, its dedicated BGP-announced IP infrastructure, and the Patroni HA PostgreSQL cluster behind every verification. Previously built high-volume email delivery infrastructure. Trained at 1337 Benguerir (École 42 network, 2019). Open-source: bgp_analyzer.