| # | Village / Locality | Post Office | PIN Code | Sub District | Type |
|---|---|---|---|---|---|
| 1101 | Sewaipatti | Bajpatti SO | 📍 843314 | Bajpatti | Post Office - PO |
| 1102 | Sewaipatti | Siwaipaiti BO | 📍 843314 | Bajpatti | Branch Post Office |
| 1103 | Shahbazpur | Sahbajpur BO | 📍 843327 | Riga | Branch Post Office |
| 1104 | Shahjahanpur | Dumharpatti BO | 📍 843320 | Pupri | Branch Post Office |
| 1105 | Shahpur | Awapur BO | 📍 843314 | Bathnaha | Branch Post Office |
| 1106 | Shahpur Sitalpatti | Riga SO | 📍 843327 | Bathnaha | Post Office - PO |
| 1107 | Shankarpur | Kumma BO | 📍 843331 | Sursand | Branch Post Office |
| 1108 | Shanti Nagar | Rajopatti BO | 📍 843302 | Dumra | Branch Post Office |
| 1109 | Sharifpur | M.Sakrauli BO | 📍 843326 | Nanpur | Branch Post Office |
| 1110 | Sharifpur | Koili BO | 📍 843333 | Nanpur | Branch Post Office |
| 1111 | Shekhauna | Dumarbana BO | 📍 843313 | Bairgania | Branch Post Office |
| 1112 | Shiuhar | Lagma Azamgarh BO | 📍 843323 | Dumra | Branch Post Office |
| 1113 | Shiunagar | Harnahiya BO | 📍 843302 | Bathnaha | Branch Post Office |
| 1114 | Shiunagar | Sitamarhi Bazar SO | 📍 843302 | Bathnaha | Post Office - PO |
| 1115 | Siari | Gauri BO | 📍 843326 | Bokhara | Branch Post Office |
| 1116 | Sihniapatti | Bakhari BO | 📍 843331 | Sursand | Branch Post Office |
| 1117 | Sihorwa | Dalkawa BO | 📍 843330 | Sonbarsa | Branch Post Office |
| 1118 | Simari | Jadupatti Bazar BO | 📍 843319 | Charaut | Branch Post Office |
| 1119 | Simiahi | Hardiya BO | 📍 843320 | Pupri | Branch Post Office |
| 1120 | Simiahi | Kumma BO | 📍 843331 | Sursand | Branch Post Office |
| 1121 | Simra | Sitamarhi HO | 📍 843301 | Dumra | Head Post Office - H |
| 1122 | Simri | Ranjitpur BO | 📍 843327 | Riga | Branch Post Office |
| 1123 | Singha Chauri | Raipur SO Sitamarhi | 📍 843326 | Bokhara | Post Office - PO |
| 1124 | Singhibahni | Singwahini BO | 📍 843317 | Sonbarsa | Branch Post Office |
| 1125 | Singrahia | Kishanpur BO | 📍 843302 | Bathnaha | Branch Post Office |
| 1126 | Singrahia | Singrahiya BO | 📍 843317 | Bathnaha | Branch Post Office |
| 1127 | Sira | Bishanpur BO | 📍 843302 | Dumra | Branch Post Office |
| 1128 | Sirahi | Sahbajpur BO | 📍 843327 | Riga | Branch Post Office |
| 1129 | Sirauli | Sirauli BO | 📍 843302 | Riga | Branch Post Office |
| 1130 | Siri Khinria | Sirkhiria BO | 📍 843117 | Runisaidpur | Branch Post Office |
| 1131 | Siropatti | Belsand SO | 📍 843316 | Belsand | Post Office - PO |
| 1132 | Sirsi | Sirsi BO | 📍 843333 | Nanpur | Branch Post Office |
| 1133 | Sirsian | Belsand SO | 📍 843316 | Belsand | Post Office - PO |
| 1134 | Sirsian | Sauli BO | 📍 843316 | Belsand | Branch Post Office |
| 1135 | Sirsian | Sirsia BO | 📍 843324 | Parihar | Branch Post Office |
| 1136 | Sirsian | Narha BO | 📍 843331 | Bathnaha | Branch Post Office |
| 1137 | Sisaula Kalan | Barharwa SO Sitamarhi | 📍 843315 | Suppi | Post Office - PO |
| 1138 | Sisaula Kalan | S. Kala BO | 📍 843315 | Suppi | Post Office - PO |
| 1139 | Siswa | Betaha BO | 📍 843324 | Parihar | Branch Post Office |
| 1140 | Siswatia | Parihar SO | 📍 843324 | Parihar | Post Office - PO |
| 1141 | Sonar | Pokharbhinda BO | 📍 843327 | Riga | Branch Post Office |
| 1142 | Sonar | Riga Colony BO | 📍 843327 | Riga | Branch Post Office |
| 1143 | Sonargawan | Parshurampur BO | 📍 843325 | Parsauni | Branch Post Office |
| 1144 | Sonaul Khan | Barharwa SO Sitamarhi | 📍 843315 | Suppi | Post Office - PO |
| 1145 | Sonaul Khan | Gharwara BO | 📍 843315 | Suppi | Branch Post Office |
| 1146 | Sonaul Mahodat | Sonaul Mahoday BO | 📍 843332 | Majorganj | Branch Post Office |
| 1147 | Sonaul Sube | Barharwa SO Sitamarhi | 📍 843315 | Suppi | Post Office - PO |
| 1148 | Sonaul Sube | Gharwara BO | 📍 843315 | Suppi | Branch Post Office |
| 1149 | Sonbarsa | K. Bhandar BO | 📍 843317 | Sonbarsa | Post Office - PO |
| 1150 | Sonbarsa | Sonbersa SO | 📍 843330 | Sonbarsa | Post Office - PO |