How do I prevent duplicate leads and contacts from getting created, when those leads and contacts use multiple email addresses to communicate?

How do I prevent duplicate leads and contacts from getting created, when those leads and contacts use multiple email addresses to communicate?

You can use unique fields to prevent duplication of leads and contacts. For instance, if a lead or contact has a different email ID but other fields, such as name, contact number, or mobile phone number are the same, you can mark name as a unique field. This will ensure that the same lead or contact isn't created more than once. You can also use the "de-duplication" and "Find and Merge" options to find existing duplicates in the leads or contacts modules and merge them into a single record.

Read more about creating unique fields here.