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How to Fix the Outlook Email Certificate Error When Sending Messages
Question details
The user is experiencing a recurring certificate warning in Outlook when attempting to send email messages, preventing secure connection.
- Product
- Microsoft Outlook
- Device & OS
- not provided
- Scenario
- Sending email messages using a POP, IMAP, or Exchange account configuration.
- Observed behavior
- Outlook displays a security warning stating the certificate name does not match the mail server, or the certificate is expired, interrupting the outgoing mail process.
Before making any changes, ensure you have your email provider's correct incoming and outgoing server hostnames and port numbers at hand, and avoid permanently accepting any invalid certificates to maintain account security.
Review Certificate Details and Update Server Settings
Verify the details of the warning to identify the mismatch, then update your Outlook account settings to match the email provider's official server information.
Often, this error occurs because the mail server name in your account settings differs from the name registered on the server's SSL certificate. Manually installing the certificate will not fix a hostname mismatch.
When the Outlook security warning dialog appears, click the 'View Certificate' button. Review the 'Issued to', 'Issued by', and 'Valid from' dates to determine if the certificate is expired or belongs to a different domain.
Go to File > Info > Account Settings > Account Settings in Outlook to check whether your email account is configured as POP, IMAP, or Exchange.
Visit your email provider's official support website to find the recommended incoming and outgoing (SMTP) server names and required SSL/TLS port numbers.
In the Account Settings window, select your email account and click 'Change' or 'Repair'. Update the incoming and outgoing server fields to exactly match the provider's recommended settings, then click 'Next' to test the connection.
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- 1. Download the Software: Navigate to the official WPS website and download the free WPS Office suite for your operating system.
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- 3. Edit and Attach: Open your Microsoft Office files directly in WPS, edit them seamlessly, and save them to attach to your outgoing emails securely.
Frequently Asked Questions
Why does Outlook say the target principal name is incorrect?
This error is triggered when the incoming or outgoing mail server name specified in your Outlook account settings does not match the domain name registered on the server's SSL certificate.
Can I simply install the certificate to fix the warning?
Installing the certificate alone usually will not resolve the problem if the root cause is an incorrect server hostname or an expired certificate on the email provider's end.
Is it safe to click 'Yes' to proceed past the certificate warning?
While clicking 'Yes' allows you to temporarily bypass the warning for that session, it is not recommended as it compromises your connection's security. It is best to correct the server settings.
Where can I find the correct server settings for my email account?
The correct IMAP, POP, or SMTP server names and port configurations can be found on the official support page or help center of your specific email service provider.
