Email addresses uploaded to Punchh (for both eClub lists or Custom Segments) must contain valid syntax in order for them to be uploaded successfully.
The main culprit regarding the "email is invalid error" tends to be related to the below rule.
In order to avoid this error, make sure the email addresses do start with or contain consecutive special characters as seen above.
If further assistance is required, submit a ticket to Punchh Support. (For help submitting a ticket, click here)