If another email was referred to, between October 13th and today, then it might have been "had told". For example:
In your email of October 17th, you told me that my account had been credited with $20. However, in your email of October 13th, you had told me that it would be credited with $40. Please explain this discrepancy.
The October 13th email predates the October 17th email which predates today's date, so "had told" would have been appropriate.
Student or Learner