Tracking Performance: They allow marketers to monitor the success of individual campaigns by tracking open rates, click-through rates, and other key metrics. Segmentation: Campaign IDs help in segmenting different campaigns, making it easier to analyze which types of emails are most effective for different target audiences. A/B Testing: By using unique IDs, marketers can compare different versions of emails to see which one performs better. Error Resolution: If there are issues with a specific campaign, the unique ID makes it easier to locate and resolve the problem quickly.