Sender Support in Outlook.com

Improve your spam reputation

Note: If you need help with a failed delivery error message, please go to Failed delivery messages from the postmaster at outlook.com, microsoft.com, or service.microsoft.com for more information.

If you are having difficulty sending email to an Outlook.com or Hotmail user, it may be because your computer's IP spam reputation is too low. Try these steps below to improve your reputation.

Tip: If you're having trouble sending email from an Outlook.com account, go here.

If you are running anti-virus software, check for the setting Internet Email Auto Protect or Internet Email Protection. If this setting is enabled, disable it and try sending a test message again.
Add your name to your outgoing email, so that “send as” is easily identifiable. See how in Outlook.com and Gmail.
Send an email to yourself, open it, and reply to it.
Include your senders in your Contacts list. See how in Outlook.com and Gmail.
Ask the recipient to add your email address to their Safe senders list. See how in Outlook and Outlook.com.
Don't put all your email recipients in BCC.
Don’t send too many emails at once, or send emails to too many people. "Too many" is of course subjective, but if you think this is an issue, reduce the frequency or volume.
Don’t send emails to people who never read or reply to your emails.
Avoid using scripting languages as they may be removed from your message. HTML scripting may help with formatting and design, but Outlook.com analyzes incoming email to remove HTML code that may be unsafe for your computer. This change is part of Microsoft's Trustworthy Computing Initiative and was made to further reduce the risk of malicious HTML content reaching our users.

There are third-party tools available, which may also help.

Before you start, you will need to know your IP address:

Make sure that your IP is not on the spam database blacklist.
Check Sender Score to gauge your email “credit worthiness”.
Try Return Path's Certification program, an accreditation and reputation service that provides Outlook.com with a list of responsible senders.

Note: Microsoft is not responsible for the content of third-party sites.

Are you managing your IP and domain's sending reputation?

Microsoft's SmartScreen® technology is designed to provide anti-spam filtering innovations for Outlook.com as well as other Microsoft products like Exchange Server, Microsoft Office Outlook and Windows Live Mail. We also leverage SPF, an email authentication technology protocol that helps address the problem of spoofing and phishing by verifying that the domain sending the email is authorized to do so. SmartScreen® email filters are influenced by a number of factors related to the sending IP, domain, authentication, list accuracy, complaint rates, content and more. Of these, one of the principal factors in driving down a sender's reputation and deliverability is their junk email complaint rate.

Are you sending email from new IPs?

IPs not previously used to send email typically don't have any reputation built up in our systems. As a result, emails from new IPs are more likely to experience deliverability issues. Once the IP has built a reputation for not sending spam, Outlook.com will typically allow for a better email delivery experience.

New IPs that are added for domains that are authenticated under existing SPF records typically experience the added benefit of inheriting some of the domain's sending reputation. If the domain has a good sending reputation new IPs may experience a faster ramp up time. A new IP can expect to be fully ramped within a couple of weeks or sooner depending on volume, list accuracy and as long as their junk email complaint rates are kept at a minimum.

Note: don't forget to update your Junk Email Reporting Program (JMRP) account with the new IPs. To update or set up a JMRP account, click here.

Are you running Anti-Virus software?

Some of the deliverability issues are the result of sender-based software configurations. If you are running anti-virus software on your firewall or SMTP server, check for the setting "Internet Email Auto Protect" or "Internet Email Protection." If this setting is enabled, disable it and try sending a test message to our servers again.

If you are currently running Symantec AntiVirus Corporate Edition 9.x or 10.x on your server, please review this article from Symantec Support.

Confirm that your DNS is set-up correctly

Try connecting to mail.hotmail.com via port 25. If you are unable to connect, then attempt to telnet over port 25 directly to our email servers (MTAs). You can find the current list of our MTAs by querying "nslookup –q=mx hotmail.com" from a command prompt (this should work in a variety of Operating Systems). Currently, the addresses for these servers are mx1.hotmail.com, mx2.hotmail.com, mx3.hotmail.com and mx4.hotmail.com. If that doesn't work, try connecting directly to the IPs. If you are able to connect directly to the IP and not mail.hotmail.com, then it is likely there is an issue with your DNS server.

Occasionally, some of the IPs in our MX record may be out of service. If you are connecting to one of these IPs your connection may timeout. Make sure you test all of our published IPs. You may also configure your outbound email server to do a round-robin DNS lookup for Outlook.com.

Are you advertising yourself as a non-routable IP?

We may not accept email from senders who fail a reverse-DNS lookup. In some cases legitimate senders advertise themselves incorrectly as a non-internet routable IP when attempting to open a connection to Outlook.com. IP addresses that are reserved for private (non-routable) networking are 192.168.0.0/16, 10.0.0.0/8, and 172.16.0.0/11 (or 192.168.0.0 - 192.168.255.255, 10.0.0.0 - 10.255.255.255, 172.16.0.0 - 172.31.255.255).

Sender services, tools, and issue submission

We have developed some tools and services which will give you more information about how our users are rating your email. These services have been tailored for senders and for ISPs. To learn more about the Sender and ISP Services, go here.

If your email complies with our policies and guidelines and you are still experiencing email delivery problems that are not addressed in the FAQ below, click here to contact support.

Note: Deliverability issues submitted using this form should only be related to the Outlook.com system, including any address @msn.com, @Outlook.com, @hotmail.com, or @live.com. We will do our best to help you troubleshoot your issue. However, submitting this information does not guarantee that any message you send to users of the Outlook.com services will be delivered.

Are you blocked for namespace mining?

Senders must not use namespace mining techniques against Outlook.com inbound email servers. This is the practice of verifying email addresses without sending (or attempting to send) emails to those addresses. This method is commonly used by malicious senders to generate lists of valid e-mail addresses that they can send spam, phishing emails or malware. Microsoft does not allow this behavior and takes action on IPs that engage in it. If any of your sending IPs is blocked for namespace mining, please check that your machines or email sending accounts are not compromised by an attacker who may be using your servers to harvest email addresses, and ensure that any method you use to validate email addresses does not use namespace mining techniques.