UK forces ISPs to keep details of all emails

deltaromeo writes: "Rules forcing internet companies to keep details of every e-mail sent in the UK are a waste of money and an attack on civil liberties, critics say.

From March all Internet Service Providers (ISPs) will by law have to keep information about every e-mail sent or received in the UK for a year. "

http://news.bbc.co.uk/1/hi/uk/7819230.stm

I'm wondering how ISP's will be able to keep the details of an email sent using webmail (eg. gmail) over https.