Gmail uses sophisticated algorithms to sort emails:

1. Factors Affecting Tab Placement:

• Content type and language used

• Sending patterns and volume

• User engagement history

• Commercial content indicators
  
  

2. Common Triggers for Promotions Tab:

• Marketing language and sales phrases

• Bulk sending patterns

• Commercial imagery and formatting

• Previous promotional sending history
  
  

3. Best Practices:

• Focus on personalized, valuable content

• Maintain clean mailing lists

• Monitor engagement metrics

• Use appropriate authentication (SPF, DKIM, DMARC)

• Consider whether Promotions tab placement aligns with your email goals

Note: While some senders try to "game" the system to reach the Primary tab, the Promotions tab is a legitimate inbox location designed to help users organize their email, not a spam folder.