cannot convert from string to system.collection.generic.list

public void SendTestEmail()
        {
            List<Person> people = new List<Person>();

            

            //people.Add(new Person("Joe", "Bloggs", "Joe.Bloggs@foo.bar"));
           people.Add(new Person("John", "Smith", "John.Smith@foo.bar"));
           // people.Add(new Person("Ann", "Other", "Ann.Other@foo.bar"));
            string emailSubject = "Training cancellation notification";
            string emailFail = "Message did not send, please check log file";

            try
            {
                foreach (Person p in people)
                {

                    //personalise message for each person, replacing "user" with firstname
                    string emailText = ("Dear " + p.FirstName +
                    " this is an email to inform you that your training course on the 1st of January has been cancelled");

                    SendEmail(emailSubject, emailText, p.EmailAddress );

                }
            }
            catch (Exception e)
            {
                Logger(e.ToString()); // catch exception
                Console.WriteLine(emailFail);

            }
        }

        private void SendEmail(string emailSubject, string emailText,
        List<Person> people)
        {

            string emailHost = "smtp.foo.bar";
            MailAddress fromAddress = new MailAddress("system@foo.bar");
            MailMessage mailing = new MailMessage();
            mailing.From = fromAddress;
            mailing.Subject = emailSubject;
            mailing.To.Add(fromAddress);
            foreach (Person person in people)
                mailing.Bcc.Add(person.EmailAddress);
            
            mailing.Body = emailText;
            SmtpClient client = new SmtpClient(emailHost);

            client.Send(mailing);
        }


        public class Person
        {
            public Person(string firstName, string lastName, string emailAddress)
            {
                FirstName = firstName;
                LastName = lastName;
                EmailAddress = emailAddress;
            }
            // changed protection level in order for mailing.Bcc.Add to attain accessibilty
            public string FirstName;
            public string LastName;
            public string EmailAddress;
        }