imperforate – 無齒票

Imperial Chinese Post (ICP) – (Imperial Post Office), 大清郵政局

Imperial Post Office – vt Imperial Chinese Post (ICP)

indemnity – 補償金

inquiry – 查詢

Inspector General of Posts – 總郵政司

Inspectorate General of Posts – 總郵政司公署

insured mail – 保價郵件

international aerogram – (international aerogramme), 國際航空郵簡

international aerogramme – vt international aerogram

inverted cancellation – 倒蓋

inverted watermark – 倒水印