In principle you can apply a rule with any header name in the email header. As far as I know, the sent date (Date) and the received date (Delivery-date) are already in the headers, but not the size of the attachment(s). I might be wrong though about the attachment(s). Someone else on this forum may confirm whether it is the case.
Here are the most common header names and their respective value:
| Header Name | Header Value |
|---|---|
| Return-Path | An email address |
| Delivered-To | An email address |
| Envelope-to | An email address |
| Delivery-date | Date received: Format example: Thu, 19 Mar 2026 17:34:56 +0000 |
| Date | Date sent: Format example: Thu, 19 Mar 2026 17:34:13 +0000 (UTC) |
| From | A sender name or organization + An email address |
| Subject | Obviously, the email subject |
| Reply-To | An email address |
| To | A name + An email address |
I suggest you use a header parser (also called email header analyzers) like this one.. These tools make email headers human readable.
Just paste your email header (Right click in the body of any email >> View Mail Header >> Copy).