The Mercer Island Post Office, located at 3040 78th Ave. S.E., will hold an open house and demonstrate how to use the Self-Service Shipping and Mailing Center (SSSMC) from 10 a.m. to 4 p.m. on Monday, May 7.

This is just in time for one of the busiest mailing days of the year, Mother’s Day, on May 13.

The SSSMC employs a touch screen and numeric keypad for customers to select products and services and receive postal information. A convenient parcel slot next to the center accepts packages up to 12 inches high by 14 inches deep and 20 inches wide.

SSSMCs do not accept cash, but only debit or credit cards, to dispense stamps and postage in any amount for Express Mail, Priority Mail, First-Class Mail and Parcel Post services. They also provide mailing information, ZIP code lookup, certified and insured mail, return receipt, delivery confirmation and other services.

The Postal Service does not receive tax dollars for operating expenses; it relies entirely on the sale of postage, products and services to fund its operations.