they can send mail with outlook with no issues.
but using SMTPauth with the same username and password he used to send me a test mail with outlook and this
SYSTEM [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session Connecting to "mail.xperiencehosting.com"
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session Connected
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session <<< 220 and/or bulk e-mail.
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session >>> EHLO extremeamd.net
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session <<< 250 HELP
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session >>> AUTH LOGIN
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session <<< 334 VXNlcm5hbWU6
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session >>> YWRtaW5Aa2lja2Fzc2FtZC5jb20=
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session <<< 334 UGFzc3dvcmQ6
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session >>> MTIwOA==
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session <<< 235 Authentication succeeded
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session >>> MAIL From:
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session <<< 250 OK
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session >>> RCPT To:
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session <<< 550 Sender verify failed
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session >>> QUIT
66.195.242.57 [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session <<< 221 mail.xperiencehosting.com closing connection
SYSTEM [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session Delivery error response error
SYSTEM [00000848] Tue, 04 Jan 2005 23:45:01 -0600 Client session Disconnected