Pixels for emails are usually implemented by putting the img script tag into the body of the email. This pixel will need to contain your AAM subdomain, as well as any key-value pairs you'd like to send into AAM to track the emails.
For example the impression could look like this: https://subdomain.demdex.net/event?d_event=imp&c_source=email&c_key1=value1
While the click would require a URL encoded redirect key (d_rd): https://subdomain.demdex.net/event?d_event=click&c_source=email&c_key2=value2&d_rd=https%3A%2F%2Fwww...
I would suggest reviewing our documentation on click and impression pixels for more: