You can do it with an "after insert/update" Business Rule on the Email table. Create a new Business Rule with the following details:
Name: Custom - Email was ignored
Table: Email [sys_email]
Advanced: Checked
When: after
Insert: Checked
Update: Checked
Filter Conditions: "Mailbox is Received" + "State changes to Ignored"
Script:
(function executeRule(current, previous) {
//create a new Incident from an ignored email
var gr = new GlideRecord("incident");
gr.initialize();
gr.short_description = "Email was skipped";
var comments = "Sender = " + current.user_id.getDisplayValue();
comments += "\nEmail subject = " + current.getValue("subject");
comments += "\nEmail content = \n\n[code]" + current.body + "[/code]";
gr.comments = comments;
var workNotes = "Error string = " + current.getValue("error_string") + "\n\n";
workNotes += "[code]<a href='" + encodeURI("/sys_email.do?sys_id=" + current.getValue("sys_id") + "&sysparm_view=inbox") + "'>Click this link to view the email record.</a>[/code]";
gr.work_notes = workNotes;
gr.insert();
})(current, previous);
You'll obviously want to add some more details, like assigning it to a particular group, etc... You can even use the "applyTemplate" method to apply the values in a Template to the Incident instead of doing it in code (would allow you to make changes without a code change).
Emails with a State of "Ignored" are ones that did not satisfy any of the conditions of your Inbound Email Actions.
This is what you would end up with in the Incident record:
The link in the Work notes would allow you to quickly jump to the Email record in case you need some more details.
