I can recive e-mail,but I can't sand them.Always is failure.Why?

Answer 1

Outgoing (SMTP) port 25 is blocked by your ISP, use 587 instead.

Here is how...

Microsoft Outlook 2002 (XP) and 2003

1. From the "Tools" menu, select "E-mail Accounts."
2. Select "View or change existing e-mail accounts," then click "Next."
3. Select your Yahoo! POP account and click the "Change" button.
4. Click "More Settings," then the "Advanced" tab.
5. Next to "Outgoing server (SMTP)," change port 25 to 587.
6. Click "OK," then "Next" and "Finish."

Answer 2

ARe you using outlook express to send and receive email. Then please check whether you have ticked the my server requires authentication in the outlook express. For more details see the link below.
http://support.microsoft.com/?kbid=171163

Answer 3

Maybe your are useing the wrong kind of sandpaper!