We was using

exec xp_sendmail @recipients='[fax:1xxxyyyzzzz]',

@message='new xp_sendmail',

@copy_recipients='xxx@xxx.com',

@subject='test'

to send fax (of course this is fax server after exchange server)

sql server-->exchange server---> fax server

after we change to use exec sp_send_dbmail @recipients='[fax:1xxxyyyzzzz]',

@body='new...