Domain Block List Office 365

I would like emails from these senders to be rejected at the gateway instead.

Domain block list office 365. The purpose of the blocked senders list is to prevent the event of false negative meaning an event in which a spam mail manages to bypass existing mail security filter that didn t manage to identify and classify the e mail as spam mail. Add the domain that you d like blocked and hit the plus sign to add it to your list. Microsoft uses the blocked senders list to protect its customers from spam spoofing and phishing attacks. Commonly called realtime blacklist dnsbl or rbl.

For more information see create block sender lists in eop. When we add a domain name or an e mail address to the blocked senders. The blacklist check will test a mail server ip address against over 100 dns based email blacklists. Your mail server s ip address that is the address your mail server uses to identify itself on the internet was tagged as a potential threat to microsoft 365 for one of a variety of reasons.

It s definitely possible that domains hosted in office 365 might be getting blacklisted from time to time but it could be a number of other factors such as domain spoofing or someone using phishing to get access and use their domain. Welcome to microsoft defender for office 365. I emphasize block because the most obvious solution a spam filter block list only marks emails from the designated senders as spam. Collectively you can think of these options as blocked sender lists.

If your mail server has been blacklisted some email you send may not be delivered. The least desirable option is to use the allowed sender list or allowed domain list in anti spam policies. You also have several options to block email from specific sources using blocked sender lists. These options include outlook blocked senders blocked sender lists or blocked domain lists in anti spam policies exchange mail flow rules also known as transport rules and the ip block list connection filtering.

Welcome to microsoft defender for office 365. You can block messages from specific email addresses or domains from reaching your inbox.