Code blocks appear to be formatted with an empty newline between each line ONLY in the HTML portion of emails. They appear correctly on both the forum itself, and in the plain text portion of the email. This is not an email formatting / CSS problem - there is an actual newline inserted in the source ONLY in the email case.
The original source text of the post looks like:
The formatted post on the website looks like:
The HTML email received, however, looks like:
In the source for the email, you can see that all newlines have been doubled: