Messages sent to remote server from a MailEnable server appear in the recipients junk mail or spam folder. This is happening for messages sent to domains such as Gmail, Outlook.com, Yahoo, etc.
There are various possibilities as to why messages can be considered as junk by remote servers and therefore delivered to a users junk email folder. Unfortunately there may be no details as to what caused the redirection in order to prevent spammers from working around any checks they do. It is worthwhile to firstly check the email headers of the message in the junk folder as there may be some hint there. Check if the "Authentication-Results" and "X-Spam-Status" email headers exist and if there is an indication of the cause in them.
Otherwise some of major reasons why emails are junked are:
For more information on setting up a PTR record please see:
The following MailEnable tool can perform a check on your domain to see if a valid PTR record exists:
Learn more about DKIM here: