: You avoid the risk of counterfeits, which the U.S. Postal Inspection Service warns are prevalent on third-party sites.

: Customer service can be inconsistent. Some Sam's Club reviewers reported delays at pickup counters or poorly packaged stamps that were ruined by adhesive tape. Online Shipping Software (Stamps.com / Pitney Bowes)

: High-volume business users or those wanting to print postage at home.

: Usually requires a monthly subscription fee, which may not be worth it for casual users. Third-Party Marketplaces (Amazon / eBay)

: Buying online via the USPS Postal Store can take several days for shipping. Major Retailers & Grocers