Can not reach to Microsoft sever to receive/send email

Follow these steps to narrow down and resolve the issue:

1. Confirm Outlook is not in offline mode (classic Outlook for Windows)
   • In classic Outlook, look at the bottom status bar. If it shows Disconnected, Working Offline, or Trying to connect…, Outlook is not reaching the mail server.
   • Go to the Send/Receive tab on the ribbon.
   • In the Preferences group, select Work Offline once to toggle back to online mode.
   • Then select Send/Receive to force a sync and test sending/receiving.
2. Verify general Internet connectivity
   • Open a browser (Microsoft Edge or Google Chrome).
   • Browse to http://www.microsoft.com and http://www.bing.com.
   • If these Microsoft sites also cannot be reached while other non‑Microsoft sites work, there may be a regional/network restriction or DNS/firewall issue affecting Microsoft services specifically. In that case, contact the local network/ISP administrator to check whether Microsoft domains are being blocked or filtered.
3. Check for large or stuck messages in Outlook (classic Outlook)
   • Open the Outbox folder.
   • Open the oldest message there.
   • If it has large attachments (for example, over 20 MB), remove the attachment or replace it with a link, then send again.
   • Large stuck messages can block subsequent mail from sending. For details, see Reduce attachment size to send large files with Outlook in the referenced article.
4. If using Outlook.com in a browser and only Microsoft mail fails
   • If the error shown is similar to “The recipient server did not accept our requests to connect”, update the Outlook.com address/alias as described in Add or remove an email alias in Outlook.com.
   • If Outlook.com still cannot send/receive while other sites work, use the Outlook.com Help menu and the Still need help? flow to reach support (requires signing in), as described in the Outlook.com article below.
5. If using Outlook for Mac
   • Confirm account settings (Tools → Accounts → select the account):
     • Verify email address, username, and password are correct.
     • Confirm any required SSL and port overrides with the email provider.
   • If the network or ISP uses a firewall or proxy:
     • Ask the ISP/network admin if connections to the mail service’s SMTP/IMAP/POP servers are blocked.
     • If an alternative SMTP server is provided, enter it under Outgoing server in the account settings.
     • If a proxy is required, configure the mail proxy in macOS System Preferences as instructed by the network admin.
6. If classic Outlook shows specific error codes
   • For errors like:
     • 0x80042109 (unable to connect to outgoing SMTP server),
     • 0x8004210a (timeout waiting for POP server),
     • or other errors listed in the article, the same troubleshooting steps in that article apply (checking server reachability, account settings, and repairing data files).
   • If Outlook uses a local .pst file, run the Inbox Repair Tool as described in the referenced article to repair the data file, then test send/receive again.
7. If none of the above works
   • Because other Internet access works but Microsoft services do not, and VPN did not help, this strongly suggests a network/ISP or regional routing/firewall issue to Microsoft endpoints.
   • In that case, contact the ISP or network administrator with the information that only Microsoft services (Outlook/Exchange/SharePoint/OneDrive/Excel Online) are unreachable, and ask them to check routing and any filtering to Microsoft domains.

References:

• I can't send or receive messages in Outlook
• I can't send or receive messages with Outlook for Mac
• Can't send or receive email in Outlook.com