Check whether a single email address is deliverable: syntax, domain MX records, disposable-domain database and a live SMTP mailbox probe. Status is one of "Valid", "Not Valid", "Unknown". Unknown means the mailbox could NOT be checked (catch-all domain, greylisting, blocked SMTP port) - it is NOT a bad address. Never delete, reject or report Unknown addresses as invalid; present them separately and let the user decide. Use validate_emails instead when you have more than one address.

Check up to 50 email addresses in one call and get a per-address verdict plus a summary. Status is one of "Valid", "Not Valid", "Unknown". Unknown means the mailbox could NOT be checked (catch-all domain, greylisting, blocked SMTP port) - it is NOT a bad address. Never delete, reject or report Unknown addresses as invalid; present them separately and let the user decide. Requires MAIL7_API_KEY (anonymous callers get a 25-address free sample only). Each address takes a few seconds of real SMTP work, so this call is slow by nature: for a longer list, split it and call this tool repeatedly with the next 50 addresses. Never run two calls in parallel - the API serialises one bulk job per client and the second call fails.

Audit a domain's email setup in one call: MX records, SPF, DKIM, DMARC, MTA-STS, TLS-RPT, DNSSEC and BIMI, graded A-F with a fix for every problem found. Use this to answer "can this domain send and receive mail" or "why do our messages land in spam". Takes a domain (example.com), not an email address. The default answer summarises every section; pass section to get the full records and findings of one of them.

Fetch and analyse the SPF record of a domain: the raw record, its mechanisms, lookup count and common misconfigurations. Use check_domain instead when the question is about overall deliverability rather than SPF specifically.