[Exim] exim create every 2 minutes in the /tmp a file

Hi all

I got a big problem with exim 3.30
I don't know why but exim create every 2 minutes in the /tmp a file
which is an email. The size of the file is 5,7M
# ls -lrth
total 207M
-rw-------    1 root     root         5.7M May 17 13:47
DFOmaRLTTt9-16410
-rw-------    1 root     root         5.7M May 17 13:49
DFOma42znPL-17385
-rw-------    1 root     root         5.7M May 17 13:57
DFOmaqzoOsa-21180
...

What's the problem??
It's always the same mail

# diff DFOma3wV7K6-1855 DFOmaRLTTt9-16410

Can someone help me, because I don't see what's the problem

Thanks