Is the Instamail option 'transparent' to the seller? Specifically, if the seller examined the 'properties' of the email, could he/she discern that the email came from AS? I'd prefer that the seller not know that I bid using AS.

Take a look at the InstaMail option. It says, "Please click here to see an example email before adding a custom message."

In that example it says, "[A short promotional offer for AuctionSniper.com will be inserted here.
This helps us get new customers and keep our costs as low as possible.]"

Top Tip: Turn it off!

R2