Since more than 1 month ago we are having our email from one of our servers systematically tagged as junk by Hotmail Smartscreen filter.
We have taken the following actions/measures without success:
- Reverse DNS matching the sender IP.
- SPF, DomainKeys and DKIM activated and pass (confirmed by firstname.lastname@example.org and by Hotmail email header itself).
- DNSBL cleaned in mxtoolbox.com, spamhaus, barracuda and Trend Micro.
- We impose hourly and daily email sending limits (90 emails/destinataries per hour and mailbox).
- Our datacenter also blocks the 25 destination port when it detects special spam or virus sending.
- We have tried different different IP's, even acquired new failover ones with previous DNSBL check and reverse DNS.
- We have tried different email addresses, even created new ones and different domains.
- The IP's that we have used are enrolled in MS JMRP and we received very few user FBL complains (one-two per month).
- Contact through Hotmail Sender Information Form and subsequent email interaction with their operators have not yielded any advancement. They always reply that "we do not see any issues with your IP as of today".
- SMTP server (postfix) logs show normal email acceptance (immediate 250 response) by Hotmail servers.
We are a sharing hosting company that provide web and email services to multiple customers in a server and IP address. It is true that we have some spam and virus infection from our clients (maxium 1 per week out of hundreds of legitimate senders) but in any case our limits and our datacenter limits hold.
We would like to know if there is a specific positive reporting link such as this one in Gmail to inform Hotmail directly from our side that our email sending is legitimate.
Otherwise we rely on our client's destinataries to positively counter-mark Hotmail spam status (if they are knowleageble and care to do so).