My outgoing (sent) emails are treated as spam

Hello,
I am in very big trouble. I use yahoomail for emails. But when i send any emails to my friends, it will be treated as spam. I don't know whats wrong. Can anybody help me with this?

Thank you in advance.

If you are sending bulk emails, it will be treated as spam. E-mail spam, also known as junk e-mail, is a subset of spam that involves nearly identical messages sent to numerous recipients by e-mail. Definitions of spam usually include the aspects that email is unsolicited and sent in bulk.

May be you can try sending emails from other accounts like gmail or hotmail. If you use scripts to send mail, then check your reverse DNS to make sure the IP address of your mail server points to the domain name that you use for sending mail. Use email authentication methods, such as SPF, and Domain Keys to prove that your emails and your domain name belong together, and to prevent spoofing of your domain name.

Point to be considered when sending email to stop your emails to be treated as spam:

• Try to avoid too many capital letters, unnecessary spacing and any unusual or over-use of punctuation.
• Examine the full header message of the email which is treated as spam to indicate the parts of message treated as spam
• Don't send emails in bulk amounts
• Avoid BCC field for putting email addresses as it will automatically treat it as spam mail