You can save messages to your Sent Items folder in two ways.

You should remember that items in any folder, including your Sent and Deleted items folders count against your overall quota.

The first way is on a per message basis. When you have the Compose Email screen open, click the Save a copy to the ‘Sent’ folder check box at the bottom of the window before sending the message. This will save only those messages that you expressly want to save and let everything else disappear. This method saves space, but you might not have a copy of a message that you might later need if you forget to check the box.

The second method is to save a copy of all messages sent to your Sent folder. To do that, open the email application by clicking on the e-mail icon in the upper right of myUSI. Then click the Options tab. Then click the Message Preferences link. Finally, check the Send a copy of all messages to ‘Sent’ folder check box and then the OK button.

Now all messages that you send will automatically be sent to your Sent items folder. This method can fill your quota quickly, so you’ll want to keep an eye on this if you get nearing or over quota messages.