freitasm: Or Telecom could just send an email saying "You owe us $8.50" or "We owe you $8.50", followed with "If you want an invoice reply to this email."
The second is my case. I have to call their helpdesk sometime to get them to mail me a cheque seeing I don't have Telecom services anymore. Or they could use Paypal to make it completely automated...
Strangely enough that's exactly what we do, plus a link to download the PDF if you want to (as it's not attached to the email).

That works pretty well for us as I don't even bother to open up the bill personally and just copy and paste the value from the email into online banking and I am done.
I do however agree with the OP that the bill size is quite large, and have raised it with the PM and Marketing folks about if an opt-out exists, or at least having two formats of the bill, the print format and the online format with much lower-res versions of the marketing pages as I personally agree keeping the PDF for archiving / tax purposes is a valid reason which would mean it is very unlikely to get printed and thus lower res images saving on file size is a reasonable request. I don't expect an answer straight away but a number of folks have been directed to this thread so they are aware of it.