How to verify a hey.com email address

The reply that matters is the one to RCPT TO, the step where the checking server names the recipient. HEY answered our made-up hey.com address with 550 5.1.1 <…@hey.com>: Recipient address rejected: User unknown. 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. HEY rejected ours, so hey.com 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.

HEY's FAQ says an address from a free trial that never turns into a paid year is recycled after 90 days and can go to someone else. Once a customer has paid for the first year, the address is theirs permanently, even if they stop paying later, and 37signals LLC runs the service.

A @hey.com address that bounces can be a lapsed trial, and an old one that works is probably a paying customer. Treat a bounce as final, and don't assume an address that once worked still belongs to the same person if it was a trial account.

Because HEY answers honestly, hey.com 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.