I use my email server to send email. I can send my emails to gmail successfully(I can find my emails in my gmail spam folder) but when I wand to send yahoo mail my emails is not recieved by yahoomail I check spam folder. but can not find it.
I'm not sure here, but I think Yahoo might block some mails completely if it thinks they are spam, i.e. they won't even show up in your spam folder. While I'm not sure about Yahoo, I know that MSN/Live behaves this way.