Doar Ivri stamp used as postage dues (last day in Haifa): Haifa registered cover posted locally unfranked on 31 May 1948 and backstamped same, marked [Haifa] Mandate type "T" tax cachet on 50m Doar Ivri (Ba 6) & box cachet "To Pay 50 mils".
The postage rate was 10 mils letter rate + 15 mils for registered mail - doubled as postage due for not being paid when mailed: the post office here required that this cover be sent registered mail (handwritten request): possibly due to the imposition of compulsory registration - required when the mail was found to contain valuable items, and the recipient had to pay the registry fee (or double that amount if the cover contained coins or jewelry; ref: Rothman/Tsachor p.110).
This was the last date when regular Doar Ivri stamps were used as postage dues in Haifa. Envelope slit open at top.
This item is being offered and priced as a philatelic cover as it originates from the "Haifa 22" post office, where a lot of philatelically prepared mail was sent in this period. In general, a lot of mail of philatelic origin came out of Haifa because the post office staff included employees associated with philatelists: posessing inside information on upcoming policy changes and postal events, and using their connections in the PO, those employees were able to get their superiors to approve mail which would otherwise not have been authorized for usage.