If $base_url not set, email address for forum incorrectly set to "<forum_name>@default"

(Apologies if this is more obvious to someone with better Drupal/Drush skills). In setting up a new site using the Forum Email Integration module, the first time through setting it up, the e-mail address shown on the main forum page shows as
"Post new forum topic Or post by email: @default"

To fix:
Set $base_url in settings.php
Disable module
Uninstall module through admin pages
Re-enable module