Microsoft Outlook, running on a Windows computer, allows you to copy emails to an external folder (i.e. a normal Windows folder outside of Outlook) by selecting the emails in Outlook and then clicking and dragging them together to the external folder. However you have to be careful when doing this that you do not overwrite any files in the external folder. The emails will generally be stored in the external folder with filenames which are the same as the Subject of the email. Obviously it is common for more than one email to have the same Subject, but click-and-drag copes with this by adding a numerical suffix, where necessary, to ensure that the emails being clicked and dragged are given unique filenames. However if you do a second click and drag, dragging further emails to the same external folder and the name of an file already in that Windows folder happens to be the same as the Subject of an email you are clicking and dragging, click and drag is not clever enough to add a suffix: it simply gives you the option of "copy and replace" or "don't copy" neither of which are satisfactory. One way to avoid this problem is to only ever click and drag to an empty external folder. If you create Windows folders with the same names as the folders within Outlook and click and drag all the emails in a folder in one go, then the problem does not arise.
This page was lasted updated in March 2017. Disclaimer