[exim] possible accept_8bitmime problems?

Hello,

a customer asked us the set accept_8bitmime=true, because his
default-installation of postfix would do something weired if our
mailserver doesn announce 8BITMIME.
On the other hand, the documentation of accept_8bitmime sounds a bit
scary to me:

----
This option causes Exim to send 8BITMIME in its response to an SMTP EHLO
command, and to accept the BODY= parameter on MAIL commands. However,
though Exim is 8-bit clean, it is not a protocol converter, and it takes
no steps to do anything special with messages received by this route.
Consequently, this option is turned off by default.
----

What could happen in the worst case?

Regards
Marten