From Sainte-Adresse to Bombay in 1918

This postcard was sent from the temporary Belgian post office in Sainte-Adresse (France) to Bombay (India) on 12 April 1918. Although there is no marking that proves arrival in India, I believe the card actually made the trip to its destination because I purchased it from a fellow in India. Postage to India at the time was 10c, making this card gravely underfranked.
See a similar postcard with the same handwriting, also mailed to Bombay from Sainte-Adresse on the same day and with grossly insufficient postage.

Characteristics: 1c+1c single Vastly insufficient postage! Unusual foreign destination
Estimated value: $8 [Actual purchase price in May 2004]