How to verify a wp.pl email address

The reply that matters is the one to RCPT TO, the step where the checking server names the recipient. WP Poczta answered our made-up wp.pl address with 550 Podane konto nie istnieje / No mailbox here by that name (#5.1.1). A 5xx code at that step is a permanent "no such mailbox", which is the same answer a real message would get, so SimpleVerifier marks the address invalid with the reason "Mailbox not found". A 250 at the same step means the mailbox exists and comes back valid.

Before trusting a "valid", a careful verifier also offers a random address that cannot exist. WP Poczta rejected ours, so wp.pl is not a catch-all: a 250 for your address is a real signal. Temporary 4xx replies (421, 450, 451) are about the connection, not the mailbox, and come back risky with "Server would not confirm" rather than invalid. Hard bounce vs soft bounce explains why that split matters.

WP Poczta's terms allow an account and its contents to be deleted after 180 days without a login, and then let another user take over the old address. A @wp.pl contact who has been silent for half a year may now reach a different person, so re-confirm older contacts rather than relying on an old opt-in.

WP's anti-spam policy rejects mail without correct reverse DNS or with SPF or DKIM not aligned to the From address, and its bulk sender rules tell senders to remove people who don't open.

Because WP Poczta answers honestly, wp.pl is one of the domains where verification removes bounces before they happen. Drop the invalid results, keep the valid ones, and re-check the risky ones later: a temporary reply on one day often turns into a clear answer the next.

A valid result only means the mailbox exists today. Addresses on an old consumer list go stale as people stop using them, so re-verify before each large send to an aged segment; how often to verify an email list gives a schedule. Upload the CSV to the verifier and download the valid, risky and invalid rows as separate files.