Customizing e-mail reports

Hi, I have searched the forums and how to’s, apologies if I have missed it somewhere.

I want to do some minor customisation to the e-mail layout

  1. subject, I want to adjust the wording as it looks a bit spammy
  2. logo image, it picks up by default the corporate logo I uploaded to the main site, I don’t want this logo (or infact any) on the e-mail

I am a more than competent php programmer so happy to delve into code to make customisations. I have had a quick look at the code base but there is nothing that pops out to me a an obvious way of doing this.

Pointers gratefully received.