Google's Gmail offers two methods for finding people you've emailed in the past. Using the search bar on your inbox, you can find every email to or from a specific person. You can also narrow the results by mail subject or folder. Alternatively, you can search your contacts list, which includes people you've added to the list, contacts from Google Plus and other people who have written you.
Searching Your Email
Click the search bar above your Gmail inbox.
Type a person's name or email address. As you type, suggestions will appear below the search bar. Either click one of the suggestions or finish typing and press "Enter."
Click any email from the selected person to open it. Alternatively, click the person's name to access a Google Plus profile, if one is available.
Searching Gmail Contacts
Click on the word "Gmail" and pick "Contacts."
Type a person's name or email address in the search bar. Suggestions will appear as you type, including people who you've communicated with, but who are not in your contact list. Click a suggestion or finish typing and press "Enter."
Select a person from the search results to view and edit contact information. If your search only turns up a single result, the contact information will load automatically.
To help find specific emails from someone, open the drop-down menu on the search bar. This displays additional options, allowing you to search individual folders or add details in addition to the person's name.
While looking for contacts, you can also find people through the category menus, instead of searching by name. Categories include groups you've created, automatic categories such as "Most Contacted" and Circles imported from Google Plus.