HTML email generated by Jira 6.x appears blank in the BlackBerry 7.x email client.

As discussed in the comments under JRA-32726 (which is a different issue), this is a known limitation of the BlackBerry email client in supporting the "viewport" tag. There's some more detail elsewhere on the web, for example:

• http://www.emailonacid.com/blog/details/C13/emailology_viewport_metatag_rendered_unusable
• https://supportforums.blackberry.com/t5/Web-and-WebWorks-Development/Viewport-issues-Web-App/td-p/1553795

The problem appears to come from atlassian-jira/WEB-INF/classes/templates/email/html/includes/header.vm:11

    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0"/>

Commenting or removing this line (and restarting Jira) results in emails displaying correctly on my BlackBerry Bold 9900.