mutt tries to auto_view all old messages

[Ulrich Lauther]

Hi all,

I upgraded to ubuntu 12.04 which implies mutt 1.5.21

Now, when I do

        mutt -f mbox

where mbox contains all my old, already read, messages,
mutt tries to open a firefox tab for each message containing html.
(I have
        auto_view text/html in .muttrc
and 
        text/html; firefox_elinks %s; needsterminal; copiousoutput;
        in .mailcap
)

I tried to fiddle with mail_check_recent, to no avail.

Compiling and installing 1.4.2.3 fixed the problem, but is there 
a configuration option in 1.5.21 to avoid this strange behaviour?

Thanks for any hints,

        ulrich