[Users] Showing mails as having been read

[senex at drofle.co.uk]

In the Preferences --> Display --> Summaries menu I can choose to mark
an email as read after so many seconds. Or I can choose to mark it as
read 'Only when opened in a new window or replied to'.

This latter works when I open an email from the main page, by double
clicking on it. However I often have several unread emails in the same
folder so, once I have opened the first one,  I move through them one by
one by using the keyboard shortcut to go to the next unread message,
that is shift-N.

This does indeed take me to the relevant message but it does not mark
it as read. When I return to the list I find that only the first new
message is marked as read.

Is there any way round this please? 

Thanks

Neil