I refer to the letter headlined, 'Passport query' from your reader Doris Da Silva (South China Morning Post, March 11).

A passport is an important document. Under normal circumstances, we would not encourage sending it by mail to prevent loss. However, in your reader's special situation, we suggest the holder of the passport to authorise a close friend or a courier despatch service to deliver the passport to the US. Sending the passport by post, double-registered, should only be a last resort.

As for the US visa, your reader may wish to seek information from the US immigration authorities.