Hmm, you could try:
1. Create a Long Text field called "Emails to find" or something
2. Copy the list of emails you need to find
3. Click the header of the "Emails to find" field and paste in the emails
3. Create a Formula field with the formula
IF(
FIND(
Email,
{Emails to find}
),
"Email found"
)
Depends on what you're trying to do though; lemme know if this doesn't work for you