public String getMailFromDomain() {
        return this.mailFromDomain;
    }
<p>
The custom MAIL FROM domain that you want the verified identity to use. The MAIL FROM domain must meet the
following criteria:
</p>
<ul>
<li>
<p>
It has to be a subdomain of the verified identity.
</p>
</li>
<li>
<p>
It can't be used to receive email.
</p>
</li>
<li>
<p>
It can't be used in a "From" address if the MAIL FROM domain is a destination for feedback forwarding emails.
</p>
</li>
</ul>

@return The custom MAIL FROM domain that you want the verified identity to use. The MAIL FROM domain must meet
        the following criteria:</p>
        <ul>
        <li>
        <p>
        It has to be a subdomain of the verified identity.
        </p>
        </li>
        <li>
        <p>
        It can't be used to receive email.
        </p>
        </li>
        <li>
        <p>
        It can't be used in a "From" address if the MAIL FROM domain is a destination for feedback forwarding
        emails.
        </p>
        </li>
aws-java-sdk-pinpointemail/src/main/java/com/amazonaws/services/pinpointemail/model/PutEmailIdentityMailFromAttributesRequest.java