SMTP Port Blocking - How to Change the SMTP Port

Some ISP's block SMTP relaying as a security precaution to thwart spammers. This means that you may need to use the ISPs mail server addresses or try a different port.

The normal SMTP port on mail servers is port 25. This is also the port that many ISP's block. On AlpineWeb Mail Servers there are two SMTP ports available for sending email:

25 (Original Standard)

587 (Newer Standard, see RFC 2476)

Changing the SMTP Port

Microsoft Outlook:

  1. Open Outlook

  2. Open Tools > Account Settings

  3. Select the appropriate email account from the list. Click Change

  4. Click More Settings

  5. Check the My outgoing server (SMTP) requires authentication box.

  6. Make sure that Use same settings as my incoming mail server is selected.

  7. Click the Advanced tab.

  8. Change the Outgoing Server (SMTP): Port field value from 25 to 587.

  9. Click OK.

  10. Click Next until you reach the Finish button.

  11. Click Finish


  • SMTP, Email, Ports, Troubleshooting
  • 0 Utilisateurs l'ont trouvée utile
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