DTOO169 - Disable dynamic caching of the form template in InfoPath eMail forms.
By default, InfoPath 2007 caches form templates when they are attached to a mail item that is recognized as an InfoPath e-mail form. When users fill out forms that open with a restricted security level, InfoPath uses the cached version of the mailed template, rather than any published version. To circumvent users filling out a published form, an attacker could e-mail an alternate version of the form, which would return the data to the sender as part of a phishing attack and could be used to gain access to confidential information.
Set the policy value for User Configuration -> Administrative Templates -> Microsoft InfoPath 2013 -> InfoPath e-mail forms 'Disable dynamic caching of the form template in InfoPath e-mail forms' to 'Enabled'.