A section of your Email Metrics calculates the estimated time it will take to read your message.
PoliteMail also uses Microsoft Word tools to calculate readability scores using the Flesch Reading Ease and Flesch-Kincaid Grade Level tests. These tests base their scores on the average number of syllables per word and words per sentence.
More about this method can be found here: https://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_tests
For reading ease, the higher the score, the easier it is to understand the document. For most standard files, you want the score to be between 60 and 70.
Grade level is measured based on the United States' school grade level. For example, a score of 8.0 means that an eighth grader can understand the document. For most documents, aim for a score of approximately 7.0 to 8.0.