Cannot send emails using Outlook Express

The most common reasons for not being able to send emails through Outlook Express are wrong Outlook settings or blocked port 25 by the Internet Service provider.

Use the correct Mail Client settings:

  • Incoming mail server (POP3/IMAP server):
  • Outgoing mail server (SMTP server):
  • Username: the full e-mail address like
  • SMTP authentication must be enabled for the login to be successful.

The most common mistake is to leave "My SMTP server requires authentication checkbox" unchecked. This option should always be enabled, since SiteGround servers require such authentication. Please find below how to enable the SMTP authentication for your Outlook express mail client:

From the Tools menu select Accounts. The Internet Accounts box appears. Select the Mail tab. Your email account appears. Select the appropriate email account by clicking on its name and click the Properties button on the right. Then under the Outgoing Mail Server section check the box My server requires authentication. Do NOT check the box next to Log on using Secure Password Authentication.

Check connection to port 25

The standard port usually used for SMTP connection is port 25. Most often the reason for failed email sending is that your Internet service provider blocks this port. If this is the case we recommend that you use the alternative port 2525 for your email SMTP connection.

If you are having problems with your email, you may ask your host for assistance. SiteGround provides the best email hosting and we will assist you with any email issues you may have.

Setting up your email is easy when you have the right host by your side. If you need a reliable partner to help you resolve email issues and provide expert support, check out our email hosting services.


  1. Reply July 8, 2015 / 00:44 mikeSiteGround Team

    Thanks Engr. Your solution helped me to reset my connection via sending and receiving E-mail

  2. Reply June 22, 2016 / 08:45 Yvonne LoockSiteGround Team

    Good day
    Please be so kind and explain step by step how to resolve my problem
    I cannot send e-mails get an error message: Error Ox800CCC67
    Would appreciate your help
    Kind Regards
    Yvvonne Loock

    • Reply June 24, 2016 / 10:49 Ivan StefanovSiteGround Team

      Yvonne, we'll be happy to take a look of this issue, but in order to investigate it properly, please submit a support ticket and provide my colleagues with your email settings and a screenshot of possible - this will be the fastest way issue to be sorted.

  3. Reply February 6, 2017 / 12:33 MOHANSiteGround Team

    An unknown error has occurred. Account: 'Commercial Tnvl', Server: '', Protocol: POP3, Port: 995, Secure(SSL): Yes, Error Number: 0x800C0133

    Please rectify the probelm.


    • Reply February 6, 2017 / 15:14 Ivan AtanasovSiteGround Team

      It appears that your Outlook mail client is reporting a corrupted inbox file (0x800C0133). It is related to the Inbox.dbx file which can be removed following a strict guide explained here

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