A user account is required to report new bugs or to comment into existing ones, as you may be contacted for more information if needed. This also lets other users clearly identify who is the author of comments or changes made into bugs.
If you already have an account and want to change your email address, you can change it from the Preferences page after logging in.
To request a new Sourceware Bugzilla account, please send your email address and the project you would like to create a bug report for to firstname.lastname@example.org. You should receive a response within 24 hours.
Note that there is no reason to send bug details in the email; you will provide those in the bug report once your account is activated.