Outlook 2011 sometimes send emails with a blank body

Hello

Sometimes when I send an email or reply to an email the receiver gets an email with no body. In my sent items the email has a body and looks as it should, but the receiver just gets an email with a subject and nothing in the body.

It's an Exchange account hooked up to Exchange Server 2007. We have Exclaimer mail utilities applying a signature in between.

Any help would be greatly appreciated, it's intermittent and I can't seem to find a pattern.

Thanks