VB Email Check

Hi

The product I am using has an Email test and I need it to check if an Underscore _ is used in the Customer Address and validate it but it always returns isValidEmail(CustomerEmail) as False

from the VB.Net Code

If EmailTemplates.Email.IsValidEmail(FromEmailAddress) AndAlso EmailTemplates.Email.IsValidEmail(CustomerEmail) Then
            If String.IsNullOrEmpty(AttachmentType) AndAlso String.IsNullOrEmpty(AttachmentName) AndAlso Attachment Is Nothing Then
                'There is no attachements
                EmailTemplates.Email.SendMessage(EmailTemplate.EmailBody, CustomerEmail, Nothing, Nothing, EmailTemplate.EmailSubject, FromEmailAddress, EmailRetentionPeriod, SourceSystemId)
            Else
                EmailTemplates.Email.SendMessage(EmailTemplate.EmailBody, CustomerEmail, Nothing, Nothing, EmailTemplate.EmailSubject, FromEmailAddress, EmailRetentionPeriod, SourceSystemId, AttachmentType, AttachmentName, Attachment)
            End If
        End If

It goes to a section in a File with a .cs extension

public static bool IsValidEmail(string email)
        {

            bool isEmail = Regex.IsMatch(email, @"\A(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?)\Z", RegexOptions.IgnoreCase);
                     
            //make sure an email address was provided
            if (string.IsNullOrEmpty(email))
            {
                isEmail = false;
            }
            else
            {
                //use IsMatch to validate the address
                isEmail = check.IsMatch(email);
            }
            //return the value to the calling method
            return isEmail;
        }
    }