FVWM: browser used on input mail

hi,
I have the following problem:
when reading a mail from input, and clicking on a link, the browser used
is not the one set in .alpinerc, but opera.
I checked that "opera" in not present in any mailcap file.
Once the mail saved in a folder, my mailcap is actually used.

any explanation?

best regards,
-- 
Pierre Frenkiel