| Abbreviation | Definition |
|---|---|
| SSPC | Self-Service Postal Center |
| SSPU | Self Service Postal Unit |
| SSVE | Self Service Vending Equipment |
| ST | Saint |
| ST | Sao Tome and Principe |
| ST | Stop |
| STE | Suite |
| STS | Supervisory Training System |
| SV | El Salvador |
| SV | Sacs Vides (empty mail bags) |
| SVM | Stamp Vending Machine |
| SWYB | Scan Where You Band |
| SY | Syria |
| SZ | Swaziland |
| TARIF | Tracking and Reduction in Force |
| TC | Turks and Caicos Islands |
| TCE | Terrace |
| TD | Chad |
| TF | French Southern Territories |
| TG | Togo |