Several factors can trigger spam filters, including:
- Excessive Use of Capital Letters and Exclamation Marks: These are often seen as aggressive and spammy. - Suspicious Links: Including links that lead to suspicious or blacklisted domains. - Poorly Formatted HTML: Incorrectly formatted HTML can signal sloppy or automated email creation. - High Image-to-Text Ratio: Emails with too many images and not enough text can appear suspicious.