SMTP and characters conversion

Hello,
I'm working with an AIX 5.3
This server receive emails from an application (ServiceDesk management) and these emails are read and integrated in another application via an EAI. I work for a french company with french people that write in french : with accentued characters (�,�,�,...). Sadly, accentued characters are lost when the message is received by my sendmail on AIX server. All accentued characters are replaced by special characters, some visible and some, not. Could you please share your experience on this kind of configuration ?
Thanks in advance.
D.

stupid question probably but ... you do have the french character sets installed on your box?

If I run locale -a, this is the answer :
C
POSIX
en_US
en_US.8859-15
en_US.ISO8859-1
fr_FR
fr_FR.8859-15
fr_FR.8859-15@euro
fr_FR.8859-15@preeuro
fr_FR.IBM-1252
fr_FR.IBM-1252@euro
fr_FR.IBM-1252@preeuro
fr_FR.ISO8859-1

So, I gather that both english and french character set are installed, non ?
Thanks for your help.