I get this error if anyone sends an mail to otrs.

 

Malformed UTF-8 character (unexpected non-continuation byte 0xdf, immediately after start byte 0xfc) in substitution (s///) at /opt/otrs/Kernel/System/Ticket/Article.pm line 101.

 

If I reply and he/she sends angain, this error is not logged.

 

What can this be??