[exim] Spambox cfg for remote delivery?

Hi folks,

Some time ago I devised a spambox configuration for Exim so that
messages that are flagged by only one or two types of filters will end
up in a user's spambox. The transport looks like this:

spambox:
debug_print = "T: appendfile for $local_part@$domain"
driver = appendfile
file = /home/$local_part/mail/Spambox
delivery_date_add
envelope_to_add
return_path_add
group = mail
mode = 0660
mode_fail_narrower = false

It works like a treat, but now I want these messages to instead be
sent to a different account on a different mail server. For instance,
a message for bob@??? arriving at mx1.example.com and flagged
as spam would be sent on to bob-spam@???.

Is such an Exim transport configuration possible? If so, what would it
look like?

Thanks,

Jaap