I am looking for a program with which I can put all the received e-mail addresses within a certain time period into and Excel program so I can determine how many different people I received e-mails from.
The program's price is 49 $ and can be obtained from the official website of the developer. To obtain what you need, it's best to export the emails to one of the format supported by the application and then import them into Excel. This is a file conversion software that allows you to convert between various email file formats.
