Receiving a flood of emails from "Postmaster" is bad news. It means that your email address has been harvested by hackers. ... When the email address they send to has been discontinued, the postmaster sends an automated message to the "reply to" address--yours. That is why you are getting emails from the postmaster.

Is postmaster a spam?

Since most domains have a postmaster address, it is commonly targeted by spamming operations. Even if not directly spammed, a postmaster address may be sent bounced spam from other servers that mistakenly trust fake return-paths commonly used in spam.

Who is postmaster outlook?

This site provides information to information technology professionals who administer systems that send email to and receive email from Outlook.com. It also provides some information about how users with Outlook.com accounts can report junk email and phishing attempts.