Topic

SMTP mailbox probing

Opening an SMTP conversation with a domain's mail server to learn whether a specific mailbox exists, reading the numeric reply code rather than sending the message.

Current clusters

build1 publisher

Port 25 decides which email check you can actually run

An MX lookup is one DNS query proving a domain has mail servers. Confirming a specific mailbox means opening port 25 from an IP that Gmail will answer, so MailProbe ships that check only in its self-hosted build.

Publishers:dev.to

Reality

Evidence40
Adoption: Insufficient
Hype gap+10
Incentives70
Confidence55