Based on the given sentences above, the one that is punctuated correctly is the second sentence: She sends an email therefore, to her instructor and advisor. What makes the first sentence incorrect is that, it has no period at the end of the sentence. Hope this answer helps.
Explanation: if it is past tense that would be correct but its not right? do that means that instead of was 8:15, it would be but it is 8:15, because this is not past tense.
