util

func VerifyEmailExists ¶

func VerifyEmailExists(ctx context.Context, address string) (bool, string)

VerifyEmailExists performs a best-effort SMTP-level verification by connecting to the recipient domain's MX and issuing RCPT TO. Many servers may greylist or disable VRFY/RCPT probes; this returns (false, reason) on any definitive negative (e.g., 550) and on transport errors provides a reason string. It honors the provided context for timeout/cancel.

Why not use gsmail (github.com/gsoultan/gsmail)? - gsmail is for *sending* full MIME emails via *authenticated* SMTP (e.g., Gmail). - This is a *probe* (anonymous MX:25 RCPT check, no auth/body/delivery/spam risk). - Custom: stdlib-only, lightweight (~50 lines), KISS/no bloat.