Changing the default "ehlo" to hide antispam technologie used ?

Hello,

running a VM with Sophos Email Appliance, i'd like to change de default "ehlo" used in order to hide the antispam technologie i use.

is there a way to do it ? how ?

NB : actually, here is what is returned by the appliance : 220 mx1.mydomain.com ESMTP Sophos Email Appliance (better would be : 220 mx1.mydomain.com ESMTP Pleased to meet you)

thanks

Florent