There should be no problems sending packages of the herbal tea to your friend. No import prohibitions for herbal teas. Singapore also trades in teas and coffees (see reference links below).
You might also like to know that Celestial Seasonings Inc's global distributor network lists this company in Singapore. If you wish, you could contact them to see if they currently stock Celestial tea (website may not be up to date):
YHS (Singapore) Pte. Ltd.
3 Senoko Way
Singapore 758057
65 6752 2122
65 6752 3122 (fax) http://www.yeos.com.sg/content.nsf/contactus/contactus
http://www.celestialseasonings.com/international/global_products.php
Reference Articles
General Import Prohibitions (List of things not to be brought into Singapore) :
http://www.fedex.com/us/international/irc/profiles/irc_sg_profile.html?gtmcc=us#C04
Singapore also trades (imports and exports) in herbal teas :
http://dir.indiamart.com/foreignimporters/ag_tea.html
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Hope this helps and that you will accept my help!
