Why did a recheck give a different result?

Greylisting (a server delays unknown senders), a mailbox that was full, a temporary server problem, or a change to the domain’s mail setup.

Trust the newer one, and if they keep flipping treat the address as uncertain: segment it and send a small test.

Each check that returns a billed status costs 1 credit. Unknown is not billed.

If results flip often for one domain, the domain’s servers may not give consistent answers.

• What does unknown mean?
• Greylisting
• Verification results
• Help center