One option in POP3 is the option to “Leave mail on server” after downloading it. If this is something you require, then we strongly recommend configuring your email to use the IMAP protocol [POP3-IMAP Comparison]. We do not recommend the “Leave mail on server” option if using the POP3 protocol. When implemented, this feature forces the downloading of the same emails many times which can drain your bandwidth, server resources and your disk space. Therefore, when setting up your email program, make sure there is not a checkmark next to “Leave a copy of messages on the server”: Today’s mail clients such as Microsoft Outlook, let you schedule automatic Send/Receive functions at desired intervals. We suggest you set yours to check for new mail every 15 minutes:

Although IMAP email is kept on the server, emails can be cached on a local machine for offline use. Deleting these cached emails does not delete them from the server. Deleted messages have a line through them. You can also permanently remove deleted messages by “Purging” them. When you purge deleted messages, they are deleted from the server and cannot be restored. We recommend purging the Deleted Items folder periodically to avoid excess storage space charges. To do this, click on “Edit” then “Purge Deleted Messages”: