Your email service provider does not provide the option of logging in using a secure connection for IMAP.
In order to establish a secure connection, your email server must provide a certificate to Outlook in order to prove its identity. The certificate that your email server is providing is valid. However, the domain name (the portion of your email address that appears after the @ symbol) is not listed in the certificate. Without this, Outlook cannot guarantee that you’re connecting to your email server.
You might still be able to connect, but your connection will not be secure. This is a problem with your email service, so you'll need to contact your IT Admin or email service provider to resolve this issue. Please let them know that their email domain presented does not match the common name or subject alternate names (SANs) in their certificate. Please note that the Outlook Mobile Support team is unable to resolve this issue for you.
