My colleague went on vacation and only used his iPhone to view and send emails for 2 weeks. His computer was on, but Outlook was not open. HE cleaned-out (deleted) lots of emails from his iPhone this morning. His outlook is missing 2 weeks of emails, before today.
That is, his inbox has emails before 2 weeks ago, and then emails of today. The option to leave copies of messages on the server was checked. The option to delete messages from the server, after 2 weeks was also selected, although I have disabled that option now. This option shouldn't have deleted last week's emails, in any case.