I have written before about the changes originally introduced in Sage CRM 2020 R1 to "ensure that a Person, Company or Lead record being added to the system has a unique email address".
Enforcing unique email addresses, Mailchimp improvements and identity matching
The behaviour behind the automatic detection of duplicate emails has been fine tuned. When it was first introduced the "Detect duplicate emails option" prevented the creation of two records with the same email address regardless of the record type. That failed to allow for the need to keep distinct the person, company and lead email addresses.
Now in Sage CRM 2020 R2 when the Detect duplicate emails option is enabled, it a user using the same email address to create two records of the same type. So duplication is prevented within the Company, Person, or Lead entities. You will not be able to create two Person records with the same email address but you can create a Person, a Lead, and a Company record with the same email address.
Every database-driven system has a way to enforce uniqueness to avoid duplicate records and to provide identity Matching. For many systems identity matching hinges on connecting users with their unique, portable, long-term central identifier - namely their email address. An email address can be used across multiple system to create a single, unified picture of your customer.
It is the 'common shared data item' that's developers to stitch together disparate data points or data sources, such as postal addresses, mobile IDs and social media 'handles'.
The diagram shows how the use of identity matching coupled with Sage CRM's powerful REST API can enable customer centric integration capabilities.