Trust me, this only happens when you actually are sending out spam. I would strongly suggest that you checked your server for malicious files on it (maybe if you are hosting a joomla/drupal/wordpress site on it, it might be hacked already and using the server to send out spam). Also, keep in mind that if you send out spam, it will still have valid SPF records, so, SPF doesn't help you enough at this. So check your access_log for POST requests, check your maillog for outgoing emails, and/or block outgoing connections to port 25 unless the uid is root or the mail account so that hacked files running as different users, can't bypass the local mta.
Also try to register with some feedback loops (hotmail and yahoo have their own, google does not believe in feedback loops:P) so that you can see the emails reported as spam that were sent out from your mailserver.
Also keep in mind that yahoo wants your emails to be signed with DKIM.
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lol NO
Trust me, this only happens when you actually are sending out spam. I would strongly suggest that you checked your server for malicious files on it (maybe if you are hosting a joomla/drupal/wordpress site on it, it might be hacked already and using the server to send out spam). Also, keep in mind that if you send out spam, it will still have valid SPF records, so, SPF doesn't help you enough at this. So check your access_log for POST requests, check your maillog for outgoing emails, and/or block outgoing connections to port 25 unless the uid is root or the mail account so that hacked files running as different users, can't bypass the local mta. Also try to register with some feedback loops (hotmail and yahoo have their own, google does not believe in feedback loops :P) so that you can see the emails reported as spam that were sent out from your mailserver.
Also keep in mind that yahoo wants your emails to be signed with DKIM.