Launch Aspire (if it's not already running). See:
To specify exactly which shared folder to crawl, create a new Content Source:
In the General tab in the Content Source Configuration window, specify basic information for the content source:
After selecting a Scheduled, specify the details, if applicable:
In the Connector tab, specify the connection information to crawl the SMTP.
In the Workflow tab, specify the workflow steps for the jobs that come out of the crawl. Drag and drop rules to determine which steps should an item follow after being crawled. These rules could be where to publish the document or transformations needed on the data before sending it to a search engine. See Workflow for more information.
After completing this step, click Save and Done to return to the Home Page.
Now that the content source is set up, the crawl can be initiated.
If there are errors, you will get a clickable "Error" flag that will take you to a detailed error message page.