I'm sorting by date/time and the messages are not in order.
This is related to the above question, "Why isn't the time displayed?" and only affects WebMail-based messages. After POP Peeper retrieves the entire message and updates the time, POP Peeper will not resort the messages. If you want the messages to resort, click the "date/time" column header twice (once to sort in reverse order, the 2nd time to sort back in the original order). If you want to ensure that the messages are always in order, you should change the retrieval option to "entire message."
Also, if POP Peeper is mixing up the month and day this could be a date formatting issue. For example, 04/02 could represent April 2 (MM/DD) or February 4 (DD/MM) depending on your locale. In these cases, POP Peeper will use the date format displayed by your computer and you will need to ensure that your webmail account displays the same format when you view the inbox. The date format often relies on the display language; for English languages, English (US) will use MM/DD and English (UK) will use DD/MM.