Stored old email addresses

A company updated it’s email address sometime ago. I deleted the original in iPhone Contacts and entered the new address at that time.

Today, I created a new email and started to enter the first three characters of the ‘old’ address.

The full address appeared in the “To:” box.

From which file somewhere on the iPhone did the ‘old’ address appear? Is it possible to excess to route out old addresses? Where is the file stored and how may I access it?

Kevin