If you received a delivery notification from the carrier, I recommend contacting your mail center directly to see if they can expedite uploading the item to your account. 

Many of our mail centers wait until a certain time of day to upload mail items. So, if it was confirmed as delivered, your mail center may not have had the opportunity to upload items for the day. 

To find their contact information in your iPostal1 account, click on Support Center in the Left-Hand Menu Bar, then Contact Us.