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When you see this message, it is usually caused by a delay between the activation of SSL and the port number you entered in your Outlook account settings. This warning indicates that the server name does not match the name in your account settings or, in the case of Exchange servers, that the address of the automatic detection file does not match the address that the server uses. This is a common problem when the administrator uses published certificates.
Many shared hosting solutions or ISPs now offer secure access to your mailbox via Secure Sockets Layer (SSL). To establish an SSL connection, a security certificate is required on the mail server. The name on this certificate must match the name you use to connect to this server. For example: mail.yourdomain.com
With shared hosting solutions, your mailbox is hosted on a mail server that also hosts mailboxes for other people’s/companies’ domains. This means that the mail server is often accessible not only via mail.yourdomain.com, but also via mail.theirdomain.com.
The server you are connected to is using a security certificate that cannot be verified. The target principal name is incorrect.
Modify your account settings
- When Outlook is open, go to the Tools menu and select Email Accounts (or Account Settings if you are using Outlook 2007 or later). When asked what you want to do, choose to edit an email account (does not apply to Outlook 2007 or later).
- Select your email address and click on Edit. From there, you can see the settings of your e-mail account.
- First, make sure that the inbox (POP3) and send (SMTP) servers are both configured at mail.yourname-of-domain.com.
- Then click on the “More Settings” button. In the screen that opens, click on the Advanced tab. Uncheck the box “This server requires an encrypted connection (SSL)” and make sure that the outgoing port number (SMTP) is 25 or 26 (26 most likely works for you because 25 is often blocked by ISPs).
- Then click again on the Outgoing Server tab and make sure that the option My outgoing server (SMTP) requires authentication is enabled and that the option Use the same settings as my incoming mail server is selected. If available, also make sure that you select “None” from the “Use the next type of encryption connection” drop-down menu.
Match Certificate Name
The first solution you should look for is that the certificate name in MS Outlooks is the same as the mail server name. To do this, follow the instructions:
- Once you have received the error, click View Certificate.
- Then click on “Issued to Name” and make sure that the name matches the name of the mail server.
- If not, change it and try again to connect. I hope that will solve your problem.
It is important to note that this may not work if the certificate has multiple names. In such a scenario, you will have to try different available names and see if one of them works. If this is not the case, you should contact your ISP to make changes to their DNS and ask for help.
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