[Exim] TLS Issue

Exim fails to complete a TLS session with an Exchange 5.5 server, using a
private domain. The line in the ESMTP dialogue it doesn't like is:

FROM:<Administrator@???> SIZE=593

Exim replies with:

501 <Administrator@???> SIZE=593: malformed address: SIZE=593 may
not follow Administrator@???>


Anyone have any clues about this?

Cheers

John