Your comments

Alternately, as I think about this...

You could also create a simple form that collects the visitors email address and message to send on to the client.

The banner would link to the form.

And you could supply both a click through and a mail conversion rate.

Hi Annaward:

My understanding is that the mailto method doesn't always work.

Personally for ads like that I've fulfilled it by uploading the banner creative as a contributed image and making the clickthrough link to that image. I set the asset to delete after the run of the banner.

Then in the caption for the image I have a "Click here to email ..." statement.

I've not gotten any complaints doing it this way. Not sure if the salepeople are passing on our workaround details either.