It's great to see you here, @chasitykendrick7. I'd like to provide some information about importing email addresses into QuickBooks Online (QBO).
Currently, the option to import email addresses from the existing vendors into QBO is unavailable. What we can do is manually enter the email address into their profile.
Here's how:
Go to the Expenses menu, then Vendors.
Select the Vendor's name to view their profile.
Click on the Edit button at the top-right.
Add the email address of your vendor.
Hit Save.
You'll want to send your suggestions about this feature directly from your QBO account.
Select the Gear icon at the top, then Feedback.
Enter your comments or product suggestions, then select Next.
You can refer to these articles for detailed steps on importing vendors' data and answers to frequently asked questions, such as the file format used in importing: