I just noticed this problem myself. The change looks okay to me. This will also make the email look more like reviewboard.
ReviewBoard: newlines and formatting are not preserved in HTML emails
Review Request #1438 — Created Feb. 26, 2010 and submitted
Comment, and reply-to-comment, emails were badly formatted because text comments were enclosed in <p> </p> flags. I replaced them with <pre> </pre> pairs, as done in the Web pages already. You would have to format a comment as 1. One 2. Two 2.1 2.2 to see the problem. Without the fix, the comment is rendered as a single line: 1. One 2. Two 2.1 2.2to see the problem. (Sorry, I think I discarded this review request by accident).
Tested on staging and production servers. Emails that are sent are now using <pre> pairs, and they are nicely formatted in Outlook 2007. However, on Outlook 2003, long lines are are not wrapped. So long comments may require to scroll right and left. I guess it's Outlook 2003 not handling <pre> correctly. I checked various browsers, and they would wrap long lines even within <pre> tags. So they behave well, as Outlook 2007.