Problem with a file attach and a special spanish word

[Benoit BURATTI]

hi,

I use kolab 2.1 , my clients are thunderbird and outlook toltec connector.
I found a problem when i send an e-mail file attach with a name like 
this "MESAS DE CONFECCIÓN.zip" if the recipient read the mail with 
thunderbird no problem but if i use outlook ot squierrlmail the file is 
not recognise, they don't know the extension outlook said me file 
attach: ATT00120.dat and squirrelmail said untitled-[2]  [ 
application/octet-stream ], with the file attach and a name like this 
without the accent it is working "MESAS DE CONFECCION.zip" .

Do you know how i can solve this problem, and who make this problem 
amavis clamav postfix?

Thank you for your help.