How to Assign the Message Date Attribute?

[J-Mac]

I captured some email messages from Gmail by first selecting the Print link in Gmail (using Firefox 3) and then Right Click>Select All>Copy to Ultra Recall.

Of course those messages come into URp as web pages, but I wanted to assign a Message Date attribute to them since these were three and four year old messages I was capturing. Can the Message Date attribute be manually applied? I tried right-click>Insert in the Item Attributes pane but Message Date is not included in the drop-down where you select the attribute you wish to assign.

If Message Date cannot be used - and it appears that it cannot - what other attribute is available that can have a date assigned? Hopefully one that I can use in searches. I realize that I could use the Item Notes for this but I was hoping to make it an attribute.

I am using Ultra Recall Pro 3d, Build 3545 on XP Pro SP2.

Thanks for any advice!

Jim