For security purposes, Trackops does not accept external email from users who are not in your contact list; you might think of your contact list as your email whitelist. This means that if you typically communicate with your clients through Trackops notifications using one email address but they respond through a different email address, there's a good chance you will not receive their responses.
To resolve this, Trackops allows you to add email aliases to your contacts in order to whitelist additional email addresses they might use when responding to you.
To add a new email alias for someone, navigate to the user's profile and find the Email field listed on the overview screen. Next, click the Add Alias link located to the right of the email. From here, simply add the additional email address you'd like to associate with this user and click Save Email Alias.
That's it, now when this contact communicates with you through Trackops via this additional alias, Trackops will recognize it and associate the communication with the right person.