Opera Help and Support

E-mail security
If you leave the authentication type for your login as "Auto", Opera will try the most secure authentication available and then work its way down the list should the first type fail. The authentication types available to you will depend on the mail server. Note that this will not encrypt your actual mail data, only your login.
Adding certificates in Opera
Reputable on-line merchants have their public keys signed by authorities, which are trusted security firms. These firms issue digital certificates that contain the public key, signed in a way that can be automatically proven. To display your current list of authorities, click "Manage certificates". Opera, like all secure browsers, comes with a set of certificates. Most of the time, certificates are fully valid, and if there is something questionable about a certificate, a warning dialog will be displayed. You may choose to proceed, but full security cannot be guaranteed at this point. Warnings may say:
Server certificate expired. Certificates have expiry dates, and they must be renewed on a regular basis by the people maintaining the site. Accepting an expired certificate does not necessarily reduce security, but consider the site you are visiting and how long it has been since the certificate expired, before accepting.
Wrong certificate name. A certificate is issued by an authority for a single site to use, and sites cannot borrow certificates from each other, as this invalidates the whole concept of certificates. Accepting a certificate belonging to another site is not recommended.
Certificate signer not found. If the signer of a certificate is not found in your list of authorities, only accept the certificate if you are absolutely confident that whoever is running the site in question, can be trusted.
Some certificates are self-signed, which means that they are signed by the Web site owners themselves, and not an authority outside the organization. If you know that the signer can be trusted, and you want all sites using this signer to be considered as safe, install the certificate to add the signer to your list of authorities. Trusting self-signed certificates from for example your employer can be considered as safe.
It is unlikely that you will need to upgrade Opera's existing certificates, as most of them will not expire for a decade or more. The necessary updates are taken care of with each new release of the Opera browser.
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