DATA command query

[Peter Ong]

Have no idea what xsavetosent is, and at the time I googled this, there was nothing on it but this
http://www.mailenable.com/enterprise-releasenotes.txt
IMP: SMTP provides new XSAVETOSENT verb so that MAPI clients have fewer problems with intermediary SMTP proxies. This will require the V1.35 MAPI client in order to function

Not even postfix's website had anything on this "verb". Is there a way to tell MailEnable to treat postfix just like a regular SMTP server, no xsavetosent etc?