Work out the query to gather up the old incidents and group them by assigned to. The filter control will give you most of what you need. Implement that as a GlideRecord query and work out how to iterate over the groups.
For each group assemble a JSON object describing the assign-to, and the incidents sys_ids, and whatever else you might want to pass to a notification.
Fire off an event and pass this object (stringified) as a param.
Create a Notification and have it respond to this event.
Put in Notification Email Scripts to read and parse the param and transform it into whatever you need, for example a table.
To run a Notification Email Script in your Message HTML:
<p><span style="font-size: 10pt;">${mail_script:rf.sr.ack.reminder.content} </span></p>
Example of setting the Subject from a Notification Email Script:
(function runMailScript( /* GlideRecord */ current, /* TemplatePrinter */ template,
/* Optional EmailOutbound */
email, /* Optional GlideRecord */ email_action,
/* Optional GlideRecord */
event) {
// parm1 is recipients
// parm2 is the rfid aka terminalid of the related Device. This makes a more useful label
// than anything from the service request itself.
email.setSubject(event.parm2 +" is being submitted for repair");
template.print("<p>If acknowledgement of...<p>");
...
})(current, template, email, email_action, event);
That will override whatever you put in the Subject field. I don't remember if the Subject allows use of mail scripts.
