Open SSMS and navigate to the Management subtree.

Right click "Database Mail" and select "Configure Database Mail".

Click [next] on the (optional) welcome screen.

Make sure the option "Set up database mail by performing the following tasks" is set and click [next]

-- You should recieve the message/question "The Database Mail feature is not available. Would you like to enable this feature?"

Click [yes] in respons to above question.

This should enable the mail feature. You can test this by executing (in another query window) the code "exec sysmail_help_status_sp". This code shouldn't throw an error anymore.

Finish the Database Mail configuration wizard by entering the Profile and Account details.