Copy of all sent mail comes to my POP3 inbox

Copy of all sent mail comes to my POP3 inbox

I use Zoho through the web interface and also have a POP3 account set up. For some reason for each e-mail that I send to anyone from the web Zoho, a copy is sent to my POP3 inbox in Outlook, which is actually very convenient because I set up a filter so that the message automatically goes into my sent box in Outlook. But I'm wondering, where is the option for this to happen or does Zoho just automatically do this?