Email to Hotmail or Gmail goes to Junk / Spam folder
Some possible reasons that cause this issue:
a) IP not set with proper SPF or PTR records.
b) IP is blacklisted and classified as spamming IP.
c) High volume of emails goes to Hotmail /Gmail server from IP or source that Hotmail/Gmail users classify as Junk or Spam mail.
If?any?of?the?IPs?were?earlier?blacklisted,?it?may?take?some?time?(estimate?about?3-7?days)?for?Gmail?and?Hotmail spam filtering?system to?establish?that?your?email gets?valid?messages. At the same time, you may request your Gmail/Hotmail user (recipient) to mark your emails as Not Junk or Spam.
For more information, you can check the following links:
Hotmail: [ http://mail.live.com/mail/junkemail.aspx ] ¨C> SmartScreen
Gmail: [ https://support.google.com/mail/answer/81126 ] ¨C> ¡°Delivery¡±
KB: [ http://gmailblog.blogspot.com/2012/03/learn-why-message-ended-up-in-your-spam.html ]
For Hotmail Users-?
Emails will still land in Junk Folder during the IP mitigation period or after IP blacklisting issue: please note that the Hotmail IP mitigation period will be 2 days (48 hours).
During this period, emails may land in the junk folder of Hotmail customers. Moreover, we recommend Users to click on ¡°Not Junk¡± option in the email folder listed above to avoid future messages from landing in junk folder and to speed up the mitigation process.
See screenshot below ¨C ¡°Not Junk¡± option:

We hope this article help you to learn why email to Hotmail or Gmail will goes to Junk / Spam folder. For more articles, please go to Knowledge Base.