Every recipient server (Hotmail, Gmail, Yahoo mail ,etc) is different and may apply different spam filtering criteria for the messages being received.
- If one recipient receives your email to the spam/junk folder does not mean all recipients are marking your emails as spam/junk.
- Spam filters are constantly changing to adapt to new techniques and these techniques are unique to every recipient server.
- This does not only depend on your hosting provider as long as the server IP is not blacklisted. However, we are responsible if the server IP is blacklisted - http://mxtoolbox.com/blacklists.aspx
STEPS TO PREVENT BEING MARKED AS SPAM
- Make sure your website is not related to and phishing or spamming activity; and also make sure your email does not contain spam keywords.
- Make sure that you are not in violation of the CAN-SPAM Act of 2003. Verify that your emails make the grade and you're not falling into common filtering rules.
- Send your customers a personal email message requesting then to mark your emails "not spam" and then the provider (Hotmail, Gmail, Yahoo mail ,etc) will also learn that pattern eventually.
- Check to make sure that your Email Authentication is enabled - You can do this in your cPanel.
- Examine your email bounces (email delivery failures). When an email bounces, it will tell you the reason for bouncing back.
- Try to contact the recipient email service provider (Hotmail, Gmail, Yahoo mail ,etc)
