Guinan made sure to check on the woman the following day and found her collapsed and unresponsive.
The Postal Service employee immediately called 911 and stayed with the customer until emergency responders arrived.
The woman was rushed to a hospital and treated for a stroke.
“Her medical needs may not have been discovered until Monday during her next delivery from Meals on Wheels,” said Victor Postmaster Susan O’Brien.
The customer is recovering from the incident.