We have a personal message in the auto Order Update but only use the B_FIRSTNAME field.

When you upload the tracking number it will mark it as posted and trigger an auto message to your buyer with a clickable link to their Order details page in eBay.

I don't think I've ever had an update message with the tracking status included in the personal message section. I did receive an auto Confirmation message a couple of weeks ago that included links to subscribe to the seller's newsletter, a link to their store and a link to their facebook page.