Most common reason for ‘Outlook cannot connect to SMTP server’ error is the wrong configuration settings of Outlook. To check the connectivity issues from user’s PC or laptop to the mail server, we get the results of ‘telnet 25’ from the users, which shows whether the user is able to connect to the SMTP port in the mail server. This can give errors while connecting to the mail server for sending or receiving mails. Though not so common, third party firewalls and anti-virus software in user PCs can block connection to certain IP ranges, which could include the server IP as well. The SMTP error in Outlook can happen due to many reasons, broadly classified into these categories – 1. What causes ‘Outlook cannot connect to SMTP server’ error In our role as Website Support for web hosting companies, this is a concern we quickly resolve for users who have email accounts hosted in the customers’ servers.Īs a one-size-fit-all solution is not possible for this error, today we’ll see what are the common causes for this error and how we resolve them for the customers. If you continue to receive this message, contact your server administrator or internet service provider (ISP).' The error message they see in their Outlook would be: Task - Sending' reported error (0x80042109) : 'Outlook cannot connect to your outgoing (SMTP) e-mail server. Often web hosts get contacted by account owners who are unable to send or receive emails via Outlook.

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