The ITS requires a package to be specified to send a report. If the reporter doesn't know which package is concerned, our documentation about bug reporting says:
If you are unable to determine which package your bug report should be filed against, please send e-mail to the Debian user mailing list asking for advice.http://www.debian.org/Bugs/Reporting
debian-user's topic is user support.
For technical discussions about development, the default group is email@example.com.
While we're at it, we shouldn't require reporters to indicate a package. If the ITS technically needs a package to be indicated, we could tell reporters to indicate a pseudo-package when they don't know, perhaps "unknown" or "default".