Fax plan that charges only to send but not receive

Anyone know of a fax plan that charges only to send faxes but not to receive them? Being able to fax PDF files would be real neat too.

A lot of fax plans I came across charge to receive faxes as well, which I think can become a problem if somebody decides faxing a lot of SPAM to a number with such a fax plan.

A lot of fax companies out there don't seem to know what unlimited receive is. Just check out this online chat convo I had with a RingCentral customer support person on 2006-05-18:

Chat InformationPlease wait for a site operator to respond.
Chat InformationYou are now chatting with 'John'
John: Welcome, I'm John, your online Sales Rep. I can help you select the right RingCentral service. So what is it that brought you to our site today?
you: Hi, do you have a plan which allows receiving unlimited faxes?
John: i am afraid not but you can choose our plan
John: Then comes FAX 2500 Plan which has 2500 pages for free and is for $59.99/month or save with an annual payment at the rate of $ 49.99 /month.
you: alright, the only problem is that if someone starts spaming me with faxes, it can cost a lot
you: I mean it's ok to pay to send faxes, because this way you can control how many you send, but there is no way to control how many you receive
John: but you can block the spam faxes
you: how is that done?
John: you can block spam faxes through your on-line account to block the numbers and area codes
you: what if they are faxing from an undisclosed number?
you: that is faxing from a "blocked number"
John: when you will block then you will not receive faxes
you: but the blockage is done by the spammer's number, right?
you: you have to know what phone number the spammer is spamming from in order to block it, right?
John: yes
John: If you have a account with our service then you can know more in your online account
you: so what I'm saying is that it is possible to send a fax from an undisclosed number, so this way there would be no number by which to block it. Do you understand?
John: let me tell you
you: ah?
John: Ok first you want to block you faxes so in your online account you can do it and then you will not receive your faxes and next
John: I am afraid you cannot send your faxes to undisclosed number
you: dude, you don't get it, I'm not trying to send faxes to undisclosed numbers, I'm trying to block spam faxes that may come from undisclosed numbers
John: Please expain your quesion a litter more .
John: Thanks
you: you don't seem to understand english too well. Are you in India or something?
John: We are based in CA
John: Kindly explain little more
John: Thanks
you: what is it you do not understand?
John: Do you want to spam your faxes from undisclosed number?
you: no you moron, I don't want to receive spam from undisclosed numbers
John: I can understand your quesion
John: You want to send your faxes from a undisclosed number so
John: I am afraid you cannot do it
you: do you understand the difference between terms 'send' and 'receive'?
John: Yeah
you: I don't think so, your understanding of English appears to be limited