The password caching policy is intransparent, leading to situations in which the careful user might not be willing to enter her password, because she does not trust the popup (as it popped up for unknown reasons).

Also I havent had this in version 4:4.5~20100910.1175630-1maemo6.1174786, in earlier versions I was often asked to enter my password after the success notification of an email-sending operation, which felt weird, too.

One solution would be displaying an introductory text, the first time that passwords are setup (although this might be experienced as annoying by users), or link a text from "each and every" passwort entry (a "why do I have to enter my password now"- button). Optionally, this button might be disabled in a "I understood - don't ask me again"- fashion.