I am having a problem when I am sending out emails to people, my emails are going directly to their junk mail. Never had this problem in the past, not sure why this is happening?

Hi Konrad Hee

I understand you are having problem with emails sent from Outlook.com being delivered to recipients’ Junk/Spam folders. 

Could you confirm:  

• Are you sending from an @outlook.com / @hotmail.com address, or a custom domain address using Outlook.com web?  
• Does this happen for all recipients or only certain providers (Gmail, Yahoo, Outlook.com, Microsoft 365, etc.)? 
• Are you sending to many recipients at once (newsletter/invites), or just 1:1 mail? 

I would love to hear from you. Have a lovely day!

When messages suddenly start going to recipients’ Junk folders, it is usually because the sending address or IP has developed a poor spam reputation, or the content/headers of the messages are being classified as spam by the recipient’s service.

For Outlook.com and Microsoft 365 recipients specifically, the following can cause this behavior:

1. Low IP or sender reputation
   • Microsoft may treat your sending IP or address as suspicious if there has been spam-like activity in the past.
   • If recipients are in Microsoft 365 and you receive Non-Delivery Reports (NDRs) mentioning banned or blocked IPs (for example, 550 5.7.606-649 Access denied, banned sending IP [x.x.x.x]), the sender must follow the instructions in the NDR or use the delist portal described in External senders - Troubleshoot email sent to Microsoft 365.
2. Incorrect IP/DNS configuration
   • Microsoft might not accept or may heavily filter email from senders that fail reverse DNS checks or that advertise themselves as non-routable/private IP ranges (for example, 192.168.x.x, 10.x.x.x, 172.16–31.x.x).
   • If your mail server is advertising a private IP in HELO/EHLO or lacks proper reverse DNS, Microsoft 365 can treat messages as spam.
3. Content or pattern looks like spam
   • Certain phrases, formatting, or attachment patterns can increase spam scores.
   • If recipients see your messages in Junk, they can help by marking them as “Not junk” and adding your address to their Contacts or Safe senders list, which can improve your reputation over time.
4. Recipient-side spam handling
   • If the recipients use Outlook.com or Microsoft 365, they can submit misclassified messages (false positives) to Microsoft for analysis as described in External senders - Troubleshoot email sent to Microsoft 365 under “My email landed in the recipient's Junk Email folder.” This helps adjust filters so similar messages are less likely to go to Junk in future.

To improve deliverability:

• Ensure your sending server has correct reverse DNS and does not advertise a private/nonroutable IP.
• Avoid spam-like content and excessive attachments or links.
• Ask key recipients to:
  • Add the sending address to Contacts/Safe senders.
  • Mark your messages as “Not junk” when they appear in Junk.
• If you receive NDRs mentioning blocked or banned IPs, follow the instructions in the NDR and, if applicable, use the delist process referenced in the Microsoft 365 documentation.

References:

• External senders - Troubleshoot email sent to Microsoft 365
• Sender Support in Outlook.com