They might be using encryption when the password is stored in the DB but they shouldn't be storing it in a retrievable format at all, encrypted or otherwise.
They should be taking a one-way hash of the password (plus a salt). This means they can check the password you enter now matches the one you gave before but they (or some cracker with access to their DB) cannot find out what it is. Encrypting the password means a cracker would have to find the DB and the encryption key, but since the key must be on the server serving the website this is hardly inconceivable.
So if they can send you your password this means they are not following well known security best practices.
Bad practice like this is a good reason for using a different password for every website you register at.