When you use Microsoft Outlook 2010 or Outlook 2013 and have multiple accounts delivered to different *.pst files, Outlook doesn’t use the default account set in Account settings. Instead, it uses the account associated with the mailbox or *.pst file the folder you are viewing is stored in. This change in behavior doesn’t work well when an IMAP is configured to be the default email account and you have a POP3 account delivered to the default pst file.