Thanks - i will look into this, i think if it didnt actually send the email it would be ok, as the user can send it form the case, the important part is attaching the transaction PDF so its easy to attach to a case email. if the user has to hit email and then attach it, that will be a workable solution.
We dont want to use the email from the transaction itself as the client has different "brands" for different subs, but the same people workings from them. So one transaction might need to be sent as customerservice@brand1 and the next might be customerservice@brand2 , we had been looking at some other options, Cases has the profiles so can cope with this, the case option gives them flexibility to also track requests and KPI's in one spot.
The alternative was to have a custom workflow to send the email from the transaction and have it pull the correct email form the sub record. We do this with automated invoices and order acknowledgements already, but they thought if they funnelled email sending by users to be from cases, its also easier to track workload and KPI's a little easier. I might get them to flesh out the process in more detail before i muck around with it!