i am not receiving mails on outlook which are not belongs to microsoft services

Hi ZainUlAbideen, 

Welcome to the Q&A Community, 

I’m here to assist your problem. 

Several factors could explain why your Outlook account isn’t receiving emails from non-Microsoft services: 

1. Modern Authentication Requirement:  
   • Microsoft has phased out legacy authentication (e.g., basic IMAP/POP) for Outlook.com and Microsoft 365 accounts, requiring modern authentication (OAuth 2.0) for third-party apps. If the non-Microsoft service or app (e.g., Gmail, Yahoo, or a custom CRM) uses outdated protocols or lacks support for modern authentication, it can’t connect to your Outlook mailbox to send or receive emails. 
   1. IMAP/POP Settings Misconfiguration:  
      • If you’ve added your Outlook email to a non-Microsoft app using IMAP or POP settings, incorrect server details (e.g., imap-mail.outlook.com on port 993 with SSL/TLS) or disabled protocols could block incoming mail. Microsoft requires these to be correctly configured, and some apps fail to handle this properly. 
      1. Blocked Senders or Spam Filters:  
         • Outlook’s robust spam filters might be redirecting emails from non-Microsoft services to the Junk Email folder, especially if they’re flagged as suspicious (e.g., new senders or unrecognized domains). This is more likely if the service uses automated emails that trigger Microsoft’s security rules. 
         1. Account or Mailbox Restrictions:  
            • Your Microsoft account might have restrictions (e.g., set by an admin in a work/school environment) that limit connections to third-party services. For instance, IMAP/POP might be disabled, or external access could be blocked in the Exchange admin center. 
            1. Forwarding or Rule Issues:  
               • If you’ve set up email forwarding to another account or created rules (e.g., to move emails to folders), these might inadvertently filter out non-Microsoft emails or fail to sync them back to Outlook. 
               1. Service or App-Specific Problems:  
                  • The non-Microsoft service might be using an invalid email address, have a full mailbox on their end, or fail to authenticate with Outlook’s servers, resulting in bounced or undelivered emails. 

Since you’re using an Outlook account linked to a Microsoft account (likely Outlook.com or a Microsoft 365 work/school account), the steps below will help you troubleshoot and resolve the issue. If you’re not the admin (e.g., for a work account), you may need to involve your IT department. 

1. Check Junk Email and Blocked Senders:  
   • Open Outlook.com or the Outlook desktop app > Go to Junk Email folder. 
     • Look for emails from the non-Microsoft service. If present, right-click > Mark as not junk > Move to Inbox. 
       • Check Settings > Mail > Junk email > Blocked senders and domains > Remove any relevant entries. 
       1. Verify IMAP/POP Settings:  
          • If using a third-party app, ensure correct settings:  

            - **IMAP Server**: imap-mail.outlook.com, Port 993, SSL/TLS 
            
                  - **SMTP Server**: smtp-mail.outlook.com, Port 587, STARTTLS 
            
                        - Use your full email and app password (see below for app password creation). 
            
                           - In Outlook.com > Settings > Mail > Sync email > Check if IMAP is enabled (for Microsoft 365, admin must enable it in Exchange admin center). 
            

2. Create an App Password for Third-Party Apps:  
   • Since modern authentication is required, go to https://account.microsoft.com/security > Advanced security options > Enable two-factor authentication (if not already on). 
   • Under "App passwords," create a new app password for the non-Microsoft service/app. 
   • Use this password (not your regular one) when setting up the email account in the app. 
   1. Check Account Restrictions (Admin Action if Needed):  
      • If it’s a work/school account, log in to the Microsoft 365 Admin Center (admin.microsoft.com) > Users > Active users > Select your account > Mail tab. 
        • Ensure "Email apps" allows IMAP/POP access. If disabled, an admin must enable it under Exchange admin center > Recipients > Mailboxes > Your account > Mailbox features. 
        1. Review Email Rules and Forwarding:  
           • In Outlook.com > Settings > Mail > Rules > Check for rules moving or deleting emails from non-Microsoft senders. 
             • Under Forwarding, ensure it’s not redirecting emails elsewhere without a copy kept. 
             1. Test with a New Email and Contact Support:  
                • Send a test email from a non-Microsoft service (e.g., Gmail) to your Outlook address. 
                  • If it fails, check the sender’s outbox for a non-delivery report (NDR) or contact the service’s support to verify they support modern authentication. 
                    • If unresolved, use the Microsoft 365 Admin Center > Support > New service request, providing your email address and details of the issue. 

As a forum moderator with a limited scope of knowledge, I hope you find my answer helpful. Please know that I've done my best to assist you."  

Thank you for your kindness and understanding. If you need anything else, please feel free to contact me.  

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