One user don t receive mail

[mul]

Hello and sorry for my english,

Someone from internet had send one email to 3 users of my domain.
Only 2 of 3 had received the email. angele.le-marchand at toto.fr don t have 
receive the email.

In message header in mailwatch, i can see this :

To: =?utf-8?Q?'LE_MARCHAND_Ang=C3=A8le'?= <angele.le-marchand at toto.fr>,
     "'ROHOU Marc'" <marc.rohou at toto.com>,
     <elodie.batard at toto.fr>

maybe the email is not receive abaout UTF error ?

thanks