Package: sylpheed Version: 3.7.0-8 Severity: grave If a new mail arrives to an account other than the current one it is changed without permission nor warning to the one receiving the email, which means all activity from then on is done unadvertingly on the switched-to account.
Considering the consequences of sending email from an account different from the one intended, like sending from a private one to a public forum (like a mailing list available on the web, or the DBTS), or using an account that is not permitted for what was unwantedly done, this makes the package mostly unusable since the consequences of can't be usually undone and can be very grave, which renders the program unusable for any serious user.