Microsoft ( and Hotmail) overview

Hotmail was one of the first web-based email services, which launched in 1996. The name Hotmail was created after HTML, or HoTMaiL. It's one of the most popular domains in the world and dominates the Brazilian, Australian, and European markets for email providers. Microsoft has established offices throughout the world to support its email infrastructure as well as to gain needed insights to tailor their tools and services to their diverse set of global users.

In 2013, Microsoft rebranded Hotmail and Windows Live Mail to

Here are some key Microsoft statistics and information:

  • Active users: 400 million
  • Emails received per day: 8 billion
  • Inbound emails that reach the inbox on average: 30% to 35%
  • Domains:,,,

In 2016, Microsoft began merging their Office 365 platform with its other email platforms. All Microsoft email will be operated on one consolidated platform by 2017.

Return Path partnership with Microsoft

In partnership with Return Path, Microsoft uses the Return Path Certification whitelist to give preferential treatment for Certified senders. Microsoft sends volume and complaint data to Return Path for use by Certified senders. Microsoft also provides data for the Consumer Network that is used in multiple Return Path products.

Return Path Certification gives senders a high probability of getting their email delivered directly to subscriber inboxes. However, Certified senders may see issues with email delivered to the spam folder at if complaint rates are high.




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Mail Transfer Agent (MTA) connections: 500

Throughput: 50 messages per connection

These can vary based on a sender's reputation.

Feedback loop (FBL) Feedback Loop application

Postmaster site


Policies and Sending Guidelines

Public monitoring services and escalation offers services to help senders gain a good understanding of the type of traffic originating from their networks and reaching customers. Senders can use this data to help stop abusive activity, such as junk mail and phishing, in order to proactively manage sending reputation.

  • Junk Mail Reporting Program (JMRP):'s JMRP provides reports for email marked as junk or phishing by users. 
    • Microsoft records a complaint when the subscriber clicks on the 'this is spam' button or if the subscriber moves the email directly to the spam or junk folder. 
  • Smart Network Data Services (SNDS): SNDS is a free service that provides high-level insight on how users rate the email they receive and the health of a sender's IP space. To receive complaint feedback through SNDS, senders should enroll at the Junk Mail Reporting Program (JMRP). Senders typically start receiving complaint feedback within SNDS in as little as 72 hours.
  • Microsoft Support: Senders in compliance with Microsoft's sending guidelines and encountering deliverability problems can submit a support request for help with troubleshooting.
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