As well as reading forum messages within Moodle, you can also have them emailed directly to your LSE inbox.
When you enter a Moodle forum, look in the top right hand corner for a link that reads "Subscribe to this forum". Clicking on this link ensures that, in future, any messages posted to that forum will be emailed to you - useful if postings are infrequent in that forum.
On the other hand, you might be receiving emails that you don't want. If this is the case, go to the forum in question and look for the "Unsubscribe from this forum" link. This just takes you off the mailing list; you'll still be able to read the forum messages online.
However, there are some forums, usually called "Announcements", from which you cannot unsubscribe. Only lecturers and teachers can post to these forums, giving them a way to send important messages to all their students.
You can also choose to receive your forum emails all in one go. See http://clt.lse.ac.uk/Help/moodle-profiles.php for more on how you can control how you receive emails from Moodle.
[Image by Jarod Carruthers on Flickr]