To reply to an email simply head to the email application you are using for the email address on the team roster and HIT reply. It's that simple.
Emails that are sent using TeamSnap are sent with the FROM address of firstname.lastname@example.org, however the sender's email address is encoded in the email as the REPLY TO address.
This means that when a recipient of an email hits the Reply button in their email application, it will put your sender's email address in the TO field in the reply email. That means the good news is that any replies to the message will still go to the correct person.