To configure spam filters in Office 365, log in to portal.office.com as an administrator. Navigate to the Microsoft 365 Defender portal by selecting Security & Compliance. Under Policies & Rules, go to Threat policies and then Anti-spam policies. Here, you can create or modify policies to block spam, phishing, and bulk emails. Adjust settings like spam confidence levels (SCL), allow/block lists, and quarantine options. Save changes and monitor reports to fine-tune filters. Additionally, configure Exchange Online Protection (EOP) settings to enhance security against malicious emails. Regularly review policies to keep up with evolving threats.