服务器拒绝了发件人地址。服务器响应为: 553
邮件发送失败, 错误编号: 服务器拒绝了发件人地址。服务器响应为: 553 authentication is required,smtp11,D8CowEBJYV7frmdR5Tf6AA--.543S2 1365749471

求解决，菜鸟不懂
代码如下

Set myMail=server.CreateObject("CDO.Message")

myMail.Subject="Sending email with CDO"
myMail.From="xiayuxuan91@163.com"
myMail.To="253305452@qq.com"
myMail.TextBody="This is a message."
myMail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/sendusing")=2
'远程 SMTP 服务器的 IP 或名称

myMail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserver") _
="smtp.163.com"
'服务器端口
myMail.Configuration.Fields.Item _
("http://schemas.microsoft.com/cdo/configuration/smtpserverport") _
=25 
myMail.Configuration.Fields.Item _
(" http://schemas.microsoft.com/cdo/configuration/sendusername")_
="xiayuxuan91" '用户名
myMail.Configuration.Fields.Item _
(" http://schemas.microsoft.com/cdo/configuration/sendpassword")_
="**************" '密码
myMail.Configuration.Fields.Item _
(" http://schemas.microsoft.com/cdo/configuration/smtpauthenticate")_
=1
myMail.Configuration.Fields.Item _
(" http://schemas.microsoft.com/cdo/configuration/smtpusessl")_
=false
myMail.Configuration.Fields.Update
myMail.Send

总提示服务器拒绝
[解决办法]
myMail.Configuration.Fields.Item _
(" http://schemas.microsoft.com/cdo/configuration/smtpaccountname")_
="xiayuxuan91@163.com"
myMail.Configuration.Fields.Item _
(" http://schemas.microsoft.com/cdo/configuration/sendusername")_
="xiayuxuan91" '用户名

加红色的部分试试