In order to speed up the publication of correspondence and to encourage debate among our readers and authors, all letters to the Editor must from now on be submitted online as eLetters. Hard-copy submissions will no longer be considered. To submit an eLetter, click ‘submit a response’ in the box at the top right of the screen when viewing online an article on which you wish to comment. If your letter is a general one, and not in response to a specific article, please ‘submit a response’ to this letter (you can also submit a general letter from the eLetters home page). We aim to publish eLetters online, if accepted, within 10 days of submission. A selection of these letters will be included in subsequent printed issues.