If you configured reportbug with an e-mail related to your hostname, you probably not configured it correctly. You need to give an SMTP server to it (preferably your primary e-mail's one), and create an app password, or enter your password (if you don't use 2FA). Then it sends an e-mail from your account as you.

The good thing about reportbug is, it works on your system with your own configuration, and walks you through the process. Microsoft Windows has a full invasive API to enable that with web browsers.

The mailing list tool used by Debian (Majordomo) is a bit backwards, but you can send command e-mails to bugs to be added to CC, or be removed, or to reclassify stuff. The best thing about it, these e-mails are also logged, keeping a nice trail of "who did what, when" kind of information. Please keep in mind that Debian e-mail lists start in 1994, so there are a lot of things to migrate when things move.

I personally also like KDE's Bugzilla, but finding correct components is a pain sometimes, so I directly use "report a bug" tool under "Help".

I don't think reportbug is perfect, but it does its thing way better than it looks. Maybe it can be improved. I need to look into it.