How Microsoft Exchange server classifies message as spam ?

Question

Hello team,

There is a question about the Microsoft Exchange server, if I receive a mail from a user@domain for example, and this mail is classified as spam, will all emails received from this domain be classified as spam also?

Answer 1

Hi @mba ，

if I receive a mail from a user@domain for example, and this mail is classified as spam, will all emails received from this domain be classified as spam also?

Not necessarily.

Microsoft Exchange provides a layered, multifaceted approach to reducing spam messages via different antispam transport agents, so the reasons why the mail is classified as spam could be various.

If this specific mail is identified as spam because its domain is prohibited from sending messages to your organization, then yes, all other mails from this domain would also be classified as spam. see Sender filtering.

If this message is classified as spam due to other factors, such as the content is assigned a high spam confidence level (SCL) or the sending email address is determined to be spoof, then the other mails received from the domain will not be impacted.

For more information about Microsoft Exchange provide antispam protection, hopefully you can find the document below helpful:

Antispam protection in Exchange Server

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