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|Scenario Task Format=Solution|Scenario Task Parent=I want to be certain of the recipient's identify identity (and vice versa)|Scenario Task Type=Impersonation|Scenario Task Description=Several systems have been developed in recent years to help email providers [https://en.wikipedia.org/wiki/Email_authentication authenticate] the sender of an email message. Most providers currently use an email authentication system to filter spam. If you are a Gmail user, you can understand how this works by reading Gmail's [https://support.google.com/mail/answer/180707?hl=en email authentication] guide. In general, you must rely on your email provider to perform sender authentication, but if you want to be sure and inspect some of the messages you receive manually, you will need to [https://www.arclab.com/en/kb/email/how-to-read-and-analyze-the-email-header-fields-spf-dkim.html learn how to read message headers] (sometimes called "message source") and authenticate them yourself with these online tools:  * [http://dkimcore.org/tools/dkimrecordcheck.html DKIM authentication ]* [http://mxtoolbox.com/spf.aspx SPF record lookup] If you would like to check that your email provider offers email authentication (for emails that you send to others), you can try the [http://dkimvalidator.com/ DKIM Validator] website. Simply send an email to the address on that page and then click to view the results. These systems either confirm the domain name (e.g. @equalit.ie) that the message was sent from or check the sender's [https://learn.equalit.ie/wiki/How_does_the_Internet_actually_work%3F#Internet_Protocol_.28IP.29_Address IP address] against a list of known malicious addresses.