If you have ever worked with a CRM you have probably seen two different records (contacts, customers, whatever they are called in your system) that represent the same person and wanted to merge them. When you try to, though, IT will not let you because they have different email addresses. It does not make sense. They are the same person! I (and probably the IT person telling you you have to treat that one person as two) agree with you. The problem is how the system is designed.
Every system with a customer database I have encountered has an email address field. This means there is only space in the system for a person to have one email address. How many email addresses do you have?
All of these systems (Salesforce, HubSpot, Netsuite, Magento, Kustomer…), many of which market themselves on being able to give you complete visibility into your company’s interactions with a person, force you to have two separate histories for that person. Yes, most systems enable you to merge these two records, but what if this person interacts with your company through the email address that no longer exists in your system? You again have two different records for the same person and their interactions with your company are no longer aggregated as you were promised.
Relationships in databases are relatively straightforward. You can have one to one relationships, a field on a record, like first name. You can have one to many relationships, many records related to one record, like companies to people. Finally you can have many to many relationships, represented by a third record type, like a product to an order represented by an order item. Since people can have more than one email address which type of relationship would you choose? As you guessed a related email address record enables you to associate many email addresses with one person and accurately represent reality.
Depending on how customizable your system is you could set up your own custom related email address record. The only problem is the person record is usually set up to nicely aggregate communication history, which your custom record would not do. The other option is to relate a number of the stand person records to a custom record, but again this custom record will not aggregate all of their histories.
An email address is not a person. Software that touts its ability to show you your company’s entire interaction with a person in one place needs to stop using an email address field and start using a related email address record.