How to verify an i.ua email address

The reply that matters is the one to RCPT TO, the step where the checking server names the recipient. I.UA Mail answered our made-up i.ua address with 550 User not found. See http://mail.i.ua/err/2/. 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. I.UA Mail rejected ours, so i.ua 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.

I.UA's help page sets out three steps: with no sign-in or POP3 collection for 90 days the mailbox stops accepting mail, 90 days later all mail is deleted, and 180 days after that the account is deleted and the login becomes available for someone else to register.

The same service issues `i.ua`, `ua.fm` and `email.ua` addresses. Because a deleted login can be registered again, an old I.UA contact may reach a different person; re-confirm Ukrainian contacts that have been quiet for a year rather than relying on an old opt-in.

Because I.UA Mail answers honestly, i.ua 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.