| Hotmail | |
|---|---|
| Domains | hotmail.com, hotmail.co.uk, hotmail.fr, hotmail.it |
| Mail routing | hotmail-com.olc.protection.outlook.com for hotmail.com in September 2026, with hotmail.co.uk, hotmail.fr and hotmail.it on a shared European host, eur.olc.protection.outlook.com. Hotmail has not been a separate mail system since the Outlook.com migration. |
| What we can resolve | We resolve some mailboxes here |
How Hotmail answers a probe
What the server does when we open a connection and ask about one address.
- Behavior matches Outlook.com exactly, because it is Outlook.com with an older domain on the envelope.
- Microsoft's throttling applies identically, so temporary failures are common on a batch of any size.
- The country variants such as hotmail.co.uk and hotmail.fr all route to the same service.
- Microsoft has reclaimed long-dormant accounts historically, so an address can change hands.
The part that catches people out
What we do about it
We probe Hotmail exactly as we probe Outlook.com, with the same pacing and the same refusal to convert a 421 into a verdict. We also flag the domain family, which is a hint about a list's age and never proof of it.
Sending to Hotmail mailboxes
Verification is one step. These are the things that decide whether the message lands.
- The same Microsoft bulk sender expectations apply as for outlook.com recipients.
- Engagement from very old consumer accounts is generally low, whatever the verification says.
- A list where hotmail.com far outnumbers outlook.com was probably built a long time ago, so check the acquisition dates.
hotmail.com and hotmail.co.uk are different namespaces
Microsoft's country domains look like spelling variants of one another, and lists get tidied on that assumption. They're separate namespaces. sam.b@hotmail.com and sam.b@hotmail.co.uk can be two unrelated people. The DNS keeps them apart as well. On September 19, 2026, hotmail.com returned hotmail-com.olc.protection.outlook.com, while hotmail.co.uk, hotmail.fr, hotmail.it and hotmail.de all returned a regional host, eur.olc.protection.outlook.com.
Say a UK retailer's import script normalizes every Hotmail variant to hotmail.com to make reporting neater. Out of 4,000 rows at hotmail.co.uk, every single one now points at a different account, or at nothing. Verification will dutifully report what it finds at the new addresses, and the invalid rate will look like a catastrophe. If a Hotmail segment fails at a rate that makes no sense, check whether something upstream rewrote the domain before blaming the age of the data.
Inactivity rules, and why the domain alone doesn't date a row
Microsoft closes consumer accounts that go two years without a sign-in. In the Hotmail years the window was far shorter, and mailboxes were emptied after months of neglect. An address collected in 2009 has had many chances to lapse, so re-verify old Hotmail rows before a reactivation campaign and expect some to have gone.
Be careful with the opposite shortcut, though. Microsoft's sign-up page has continued to offer hotmail.com as a domain choice beside outlook.com, so a Hotmail address isn't proof that the account is old. Check the sign-up form yourself if that surprises you. The better age signal is your own data: the date the row entered your system and the last time it clicked. Use the domain as a hint, and let those two dates decide which rows get a re-permission email and which stay in the main list.
Questions people ask
Do Hotmail addresses still work?
Yes. Microsoft migrated the accounts into Outlook.com rather than retiring them, so the addresses still deliver.
Can Hotmail addresses be verified?
As well as any Outlook.com address, which means moderately. Microsoft's throttling and inconsistent codes are the constraint.
Is hotmail.com a red flag on a list?
It is a soft age hint and not a quality flag. Most hotmail.com addresses on an old list are old, and old correlates with low engagement, but the domain is still offered at sign-up, so check your own dates before assuming.