[Exim] How2 change EHLO string?

Hi all:

Does anyone know how to change my Exim4 server's EHLO string?

for example:

Connecting to smtpgw.nanjing-fnst.com [203.93.220.119]:25 ... connected
SMTP<< 220 smtpgw.nanjing-fnst.com SMTP; Fri, 06 Aug 2004 09:04:47 +0800
SMTP>> EHLO fly.nanjing-fnst.com

              ^^^^^^^^^^^^^^^^^

I just want to change the fly.nanjing-fnst.com to others.

Thanks a lot

wangwei@???