Better bounce handling

I have activated the bounce handling, which on itself works fine. However, since most of my subscribers are Dutch, the bounce e-mail subject does not say 'Undeliverable', but 'Onbestelbaar', which means the same, but in Dutch.

The software does not seem to pick that up, and doesn't concern those mails as an undeliverable, and thereby doesn't remove the subscriber from RSMail. I can imagine this is the same for other languages, so an extension of the bounce handling would be great.

Furthermore, some servers attach a bounce email specifics in a attachment, rather in the mail itself. RSMail doesn't look inside any attachments, so those undeliverables are also ignored.