ESPs use a combination of rule-based systems and machine learning algorithms to filter email content. These systems evaluate multiple factors, including:
Keyword analysis: Certain words and phrases are more likely to trigger spam filters. Link scrutiny: The quality and reputation of the links included in the email. Attachment evaluation: The type and nature of attachments, if any. Sender reputation: The historical behavior of the sender’s email address. Engagement metrics: Previous interactions by the recipient with the sender's emails.