email@domain[com] someone is sending mail to our email (Fake emails)

Hello, so I don't know how to explain everything, but there is problem with one server and one domain on it.
We have domain domain.com and it has email@domain.com
Someone is sending us fake emails width pdf attachments.pdf.htm to our original email@domain.com from fake notification@domain.com
notification@domain.com doesn't exist.
Plesk mail server outgoing mail mode setting is: Send from domain IP addresses...

email@domain[com] <notification@domain[com]> someone is sending mail to our email (Fake emails)