FWIW I saw the Lonely Planet (travel site) online manager speak at an email marketing conference last year, and he said the best thing they had done (in terms o

FWIW I saw the Lonely Planet (travel site) online manager speak at an email marketing conference last year, and he said the best thing they had done (in terms of database growth) was go to single opt-in. Needless to say he got frowns from the 'best practice' people in the room, including the conference sponsors, but I'd say it's a rule not the first rule.