E-mail filtering is managed by Microsoft and they provide you with a quick and easy way to report potentially suspicious or junk e-mail.
Depending on your choice of e-mail client (Microsoft 365 Webmail or Outlook 2019) their process looks slightly different.
Microsoft 365 Webmail
Right click on the email you would like to report and hover over Security Options
Select the appropriate method of reporting depending on the email.
If it is a general spam or junk message, such as unsolicited newsletters, select Mark as junk.
If the message is requiring action on your part, such as providing login information or requesting you to contact someone, it is likely a phishing email. Select Phishing.
If you keep receiving message from this particular email address, you can select Block to stop receiving messages from that address
Outlook 2019
Left click on the email you would like to report and look in the top menu ribbon for Report Message and left click on it.
If it is a general spam or junk message, such as unsolicited newsletters, select Junk.