Minnesota Senator Says Email Tax Might Reduce Spam

indros13 writes "The Hon. Mark Dayton, Senator from Minnesota, is reportedly considering a "miniscule email tax" to counter the flood of spam. Thinking like an economist, he's obviously hoping to make mass emailing unprofitable. 'You can't say, "We want it to be totally free and unrestricted and on the other hand we want it to work smoothly and civilly," he said.' No word on how all those lobbying groups that use mass emails will respond, but I'm sure there are a few emails on the way..." Politician weasel words are part of the package, though; Dayton says a tax is "just one of the tactics that should be considered, but I don't favor it at this time."

Government control = bad

Interesting how everyone who thinks there should be a tax on email thinks that the money should go to their organization or government.

"Leave it alone," [Norquist] said. "If the government gets involved, they will mess it up."

Agreed. The point is that if "little" things like this are allow, then it's basically saying "Look, Verisign, commercializing the internet is the solution like you said!"

I likes my SpamAssassin, thanks ;^)

Re:Government control = bad

Interesting how everyone who thinks there should be a tax on email thinks that the money should go to their organization or government.

Clearly it should go to a once-a-year ice cream party for the whole Internet.

Re:He could get this right...

If the Federal Government is going to pass any law that addresses spam, it should be a law that says that every user of email is required to use a Bayesian filter. That would lead to a virtually zero response rate within months which would lead to spam going away. And, wow, all without new taxes!

The Federal Government should stay out of it. With or without a tax, a new law would cost money. You'd need enforcement to ensure that the tax is paid (or, in your example, the Bayesian filter is installed), etc . . .

In the end, the Feds would bungle every aspect of any attempted law (except maybe collecting the tax -- they're good at that).

Good intentions, bad implimentation

I think the industry as a whole would be *MUCH* better off looking for a technical solution rather than hoping for government intervention. Plus, the internet is multinational, so it's a hopeless task for the government to do anything about it. "The Road to Hell is paved with good intentions" pretty much sums up this article.

Re:Kill the demand, not the spammer

Kill the demand, not the spammer

Bugger that. Kill the damn spammer.

Re:Good intentions, bad implimentation

Agreed; I thought that it was just a matter of getting all the mail servers to use a more secure form of header that could not be forged, and then spam could be stopped at a higher level.

Besides, how in the name of the gods do you implement such a tax?

Do you tax intra-company email as well?

Do you tax email between different geographical branches of the same company?

What about instant messages? efax? VoIP?

Suppose people work around it by creating VPNs and just tunnel their email to members of the VPN by encrypted means.

Suppose you do file transfers rather than email--just have programs at each end that compile and de-compile the files into text messages, but while in transit they don't resemble email.

Methinks this whole idea is looney and it will take about a week for people to develop workarounds to completely avoid an "email tax". Leave it to a Member of Congress to destroy yet another productive sector of the economy with taxes. Grr.

Sorry I'd better go drink my coffee (kaffree actually)

-Yog

Re:Good intentions, bad implimentation

> Besides, how in the name of the gods do you
> implement such a tax?

By requiring ISPs to purchase licenses, keep records, and file reports, in the same way sales taxes are collected. The government would, of course, find other uses for those records and reports.

> Do you tax intra-company email as well?

Probably not, as long as it doesn't travel over the "public" Internet.

> Do you tax email between different geographical
> branches of the same company?

Probably, though there might be special licenses. "Legitimate" organizations would be allowed to apply for exemptions for mailing-lists. They would, of course, be required to keep records and file reports.

> What about instant messages? efax? VoIP?

A different set of taxes.

> Suppose people work around it by creating VPNs
> and just tunnel their email to members of the
> VPN by encrypted means.

Tax evasion is illegal.

> Methinks this whole idea is looney and it will
> take about a week for people to develop
> workarounds to completely avoid an "email tax".

Thereby justifying the creation of an enforcement bureaucracy with elaborate regulations. You don't think this is really about spam, do you?

Re:Good intentions, bad implimentation

I think the industry as a whole would be *MUCH* better off looking for a technical solution rather than hoping for government intervention.

Ahhha, but what would force the industry to move forward together and adopt a "new" secure public key based electronic mail protocol?

Incompetent government intervention :)

Yeah baby, bring on the e-mail tax!!

No good intentions here...

There is no good intention here. Let's say the tax passes. Spam is reduced because they don't want to pay the tax. The tax, however, is in place. Who is paying it? WE ARE! Are they going to repeal the tax now that only the innocent are paying it? NO! See, a new teat was spawned and their are "social programs" that depend on that new tax. When someone tries to repeal that tax, they will be dubbed "uncaring" and "anti-children." Furthermore, we'll hear the usual "Who is going to pay for the e-mail tax cut!?"

Re:Government control = bad

The problem with any type of fees like this is that only big spammers and corporations will be able to exploit it. I run a non-profit site that sends out approximately 50,000 emails per months. These emails are REQUESTED by the members of my site as they are updates about transactions they are involved in, notices of responses to messages they've posted in the forums and other items.

I do not make a penny running my site and have to pay most of the cost of the server and the colocation and bandwidth out of my own pocket. Even if they charged one penny per email, I could not afford an extra $500/mo or $6000 per year just for the right to send out email notices to users. I couldn't even afford $50/mo or $600/year if we charged one tenth of a penny per message.

Besides, what about system notices? And who/how will the email fee be collected? And why not just support an alternate RFC to promote more secure email standards like secure SMTP?

Re:Government control = bad

> I likes my SpamAssassin, thanks ;^)

Me too. I especially like how the last job I applied for on Monster.com got bounced by the HR person's inbox by SpamAssasin because it "looked like spam". Maybe I used too many buzzwords in my resume...

"Hire me now and enjoy as the ladies in the office will marvel at your enormous penis size relative to mine!"

Spam has made it difficult to set up legitimate servers to send legitimate e-mail to their indended recipients...

Re:Anything to get more money

Taxing childbirth might stop overpopulation.

Actually, it does. In China and Japan, at least.

First the email tax

Next, the blog post tax. Hey, it would make trolling far more expensive, right?

Between this story and the story of third world countries wanting the UN to "control" the Internet because IANA is too US-centric, I really get the idea that government-control types really have no clue what the Internet is. If you "regulate" the Internet with taxes, restrictions, etc, another network will rise to take it's place. The main feature of the Internet is relative anarchy (also called freedom). Are there rules on the net? Of course! It's called "consensus"! Deal with it.

Re:Haha!

Taxes? World-wide or what?

The funny thing that these moron legislators don't understand is, if they could collect the tax on mass e-mailing then they could just as likely just outlaw sending UCE entirely and hold the people doing it responsible. The problem is it's nearly impossible to pinpoint who is sending all this garbage. Why would they pay the e-mail tax when they're already conducting fraud?

This won't work.

This won't work. To send letters in the mail is the cost of the material, the envelope, and obviously the stamp. The US postal service has continually upped the price of sending letters, yet I seem to get MORE of those 1024 free AOL hours CD's now than ever before, and they are getting bigger and heavier and cost more to send out. I doubt a tax on sending emails will have much of an effect on spam. Spam is already SO much cheaper than snail mail, and snail mail spam still happens. I would argue that even if we levied a 37 cent tax on every email that we still would have a large amount of spam. Besides, how the hell do you enforce such a policy? Especially when emails can be sent within a particular ISP from the spammer to users with no real way for the goverment to get in there and inforce such a payment plan. This just won't work.

Re:This won't work.

yet I seem to get MORE of those 1024 free AOL hours CD's now than ever before

Ever notice there's a return address? Slap a label over your address that says 'return to sender' and drop it off in a mailbox. Imagine their mailroom problems if just 10% were returned. Usually junk mail's not worth the effort since it can just be tossed in the recycling bin, but why should my landfill fill up with these CDs and their cases? Send them back and let AOL deal with it.

Tax the whole world?

Clearly the guy is pretty clueless about email or only ever receives it from his mother down the road. How does he expect to tax email from
outside the USA? Hold the emails in some large mail spooler at the border and send a bill to the people in the foreign countries? Christ , how do people
this dumb ever get elected? Oh ... wait...

The Solution Is Already In Place

The laws are there; they just need to be applied to the fact situation.

Spammers tailor the stream of bytes to get into other people's computers, bypassing various measures the owners have taken to keep them out. Does this sound like "computer cracking". That's because it is. Did you think that computer cracking is illegal? All together now: That's because it is.

Re:Oh geeze, not again

OK, first the obvious: You can't tax e-mail sent from out the country.

Even from a strictly legal point of view, the US government can't tax e-mail sent out from the country -- export duties are expressly forbidden by the Constitution.

Just what we need to burnish America's international image: an anti-spam policy that specifically exempts Americans who spam furriners.

Tax on who?

You need to know where it came from to tax it. If we knew where it came from, we could stop it.

Besides that, it's all just data. You can't tax some packets and not others - people will just develop new protocols to avoid the taxes. Unfortunately you have to understand the technology to make sensible rules governing its use.

I'v already got bayesian filtering,

and if the rest of humanity is too stupid to do a 10 minute google search then I'm not paying for it. You want to stop spammers? Use a decent filtering scheme.

Same thing as with drug, gun, and sex ed. If the vast majority of people weren't so damn irresponsable and stupid then they'd be able to handle either not using drugs or using them responsabily (not only does this apply to marajuana, but also the likes of prozak), certain guns wouldn't need to be outlawed because some dumbfuck would press the trigger by accident and off his entire family. And finally, our kids would not only know where and when sex is ok, but why it is ok and how to make love responsabily.

Either way, if he passes a e-mail tax law, I'll just setup something else that isn't spammable like a VPN between my house and my family members that transmits txt documents into a local folder. Mabye that way the idiots who use the system won't open up sobig viruses and help to make virus problems worse.

so the next outlook virus.....

.... that infects your machine and emails everyone in your address book could cost you a few dollars? YIKES!

on a more serious note, is there a legal definition of what is spam? i consider anything about M$ Windows based products to be spam because i use a Mac, but i am sure to somebody it may be useful information.

Tax evasion

Spammers are already using viruses and hacked accounts to send the email. They won't be paying the tax the victim will.

Time for some OSS innovation?

I've never understood why this isn't something that the OSS community hasn't tried to tackle.

For business purposes, I want an email system that:

1) Is Spam free.
2) Is secure.
3) Is failsafe - i.e. if the recipient doesn't receive the message, I want to know about it.

Surely from a technical perspective, this isn't that difficult?

Why can't the OSS mail clients agree on a standard for doing this. I don't see why it shouldn't be possible, for instance, to have two mail boxes (or whatever you want to call them) for a single email address - one for "secure emails", and the other for the rest. The secure email box would only recieve emails that were from an approved address.

This could be a great way for OSS software to creep into organisations - I could tell my clients, for instance, hey, if you use Thunderbird, we can email each other more securely/without spam/in a failsafe manner. The network effects of this kind of promotion for OSS could be fantastic.

This looks like an opportunity that's going to waste for the OSS community. Come on guys, or people will start saying we don't innovate!

To defend my senator

Ok, there are already some wingnut posts on this story, so I feel the need to set the record straight:

This is not just a case of RTFA, it's a case of RTFP (post). Fortunately the post quotes Dayton as saying Dayton says a tax is "just one of the tactics that should be considered, but I don't favor it at this time.".

It's just an idea folks. Obviously we all know it isn't workable, but at least these guys are thinking about the issue in general.

There probably isn't a legislative solution, and I think Mark Dayton is open minded enough to reach that conclusion and then say it publicly. Of course, I don't think it would get as much coverage as this story, because here's a Democrat trying to raise taxes! For shame!

What about the regular mail costs?

Regular mail "costs" 37 cents, but every day I get a stack of flyers in my mailbox that are metered or something, and they come from multiple sources. Charging for email will generate a lot of revenue, but just like raising the postage stamp rate, it will have 0 effect on spam.

taxes won't

taxes won't stop criminals and scum. we already know spammers are evasive, they will just wheedle a way around the taxes the same way they wheedle into open relays and use foreign hosting.

if the government want's to do something, let them prosecute. most spammers live in the us and canada. in almost all the spamm i've ever seen their is enough fraud and misrepresentation in each email to at least bring charges in civil court with current laws.

Spammers already break the law

It's been more than adequately demonstrated that spammers already break the law. They use services belonging to other people without their consent and against their will. They commit computer crimes such as breaking into systems and spreading viruses. They frequently send ads which are themselves fraudulent; many also advertise products which are otherwise unlawful, such as quack medications and devices for stealing cable TV service. They defy existing regulations on email advertisements, such as state laws prohibiting forgery of return addresses and requiring the subject-line prefix "ADV:" on advertisements. Indeed, the spammer's common false claim that "you opted in" has been ruled an act of fraud.

The problem of spam is already a problem of laws going unenforced against an entrenched criminal element. While spamming itself may not be explicitly illegal, the act of spamming is not separable from acts which are illegal, such as fraud, conversion, and theft of services. Many (including some spammers) are under the misapprehension that because these laws go unenforced, spam is thereby legal. Indeed, the problem of enforcement is so bad that blatantly destructive acts such as denial-of-service attacks against anti-spam services have gone utterly uninvestigated by law enforcement. (This may be changing.) [spamhaus.org]

It is utterly unnecessary to create further laws which penalize ordinary Net users, in an effort to stop spammers. Indeed, such laws simply aggravate the problem already posed by spam: increasing the bother, inconvenience, and expense of using and operating the mail system. In effect, such laws would help the spammers destroy email.

If this were possible, it wouldn't be needed

If you could track spammers down and collect a tax, then you could just as easily track them down and prosecute them for fraud, which the majority of spammers commit in one way or another. All this would do is tax law-abiding citizens, and encourage more credit card fraud, viruses, trojans and ID theft on the part of Spammers so they could stay anonymous (or pay the tax with someone else's credit card). We need a new branch of government - the IT branch - because no other branch has a clue when it comes to this crap.

A better Minnesota solution

Couldn't they just send former governor Jesse "The Body" Ventura over to the spammer's place to .. explain .. the situation?

California could explore this option too.

Take Dayton at his word: he rambles

A Minnesotan here, and I like Dayton and all, but he isn't exactly the most compelling public speaker you'll find. I get the feeling when he qualified himself that he isn't dissembling, he just has a nervous habit of qualifying *everything*. ...which is a politician trick, I know...

Anyway, the point is that this is more "Hey, this might be an idea, or whatever, I really don't know," than it is "I have this secret plot I want to enact, but I'll throw you off the trail by claiming I'm unsure about it."

possible scenario

Obviously, it would be shitty to pay more for something we already know and love (or you might have email for free, in which case paying anything would stink). But here's what I like about it. They could set it up in some kind of tiered system, kinda like cell phone usage plans, where it's pretty cheap if you stay within your expected usage, but totally unreasonably expensive if you go over. So maybe you pay one penny per email sent during the month, with a cap of 500 emails sent (I'm just throwing that number out there, because it seems like a huge number for an individual). If you go over 500 emails, you pay $1 per email. You could then regulate email traffic and collect taxes at the ISP level, since they're the ones who own and control the smtp servers.

Yes, there would be implementation issues and privacy concerns, problems, etc., but if this were in place I can't help but think it would make a positive difference. And before I get slammed by everyone, I realize there are all kinds of problems with legislating spam behavior in this country. The most obvious of which is the spammer's ability to simply relocate their operation outside the U.S. border where U.S. laws will have a much more difficult time taking effect.

Keep in mind that I'm not trying to invent the solution in this post, so don't take it like I'm defending the silver bullet to the problem of spamming, or go on a crusade to prove why I'm wrong. I just think this is an interesting idea. There are problems with every other spam prevention idea, evidenced by the continued (and growing) presence of spam for the majority of people (ie, not just computer geeks; spam reduction has to work for people like our grandparents and non-nerdy friends, and it will have to be transparent for it to work).

I think the email tax seems like one of the least shitty solutions out there. Anyone else have other, not-so-shitty solutions to spam?

Mailing lists...

Just think, you subscribe to 5 high-volume mailing lists and participate heavily. You send out 300+ messages daily. Suddenly your fee gets substantial!
And if you work as user support for a small company, replying by email? Suddenly costs of operating rapidly rise. You operate a free web forum, where people subscribe and an automated reply sends them their password, and optionally get email notifications on changes in threads they watch. Your forum can't be free anymore.
I can think of a dozen other legitimate uses for sending bulk amounts of emails. Even with $0.01/email, with one email a day for some 500 users, that makes $150/month. Can easily kill any free service.

What exactly is an email?

For the purposes of this tax what exactly constitutes an email? Is it any communication on port 25? What if I use some other port? Would I get still taxed if I ftp'd a text file? What if the file were compressed. What about message board traffic? What about IRC? What about Instant Messenger? What if I mail someone a floppy with messages on it?

What happens with email from outside of the taxing jurisdiction? Does the receiver pay? (That would be cool. I could just 'drive' across the border and mail bomb people I don't like. POW! right in the checkbook!)

I used to think "sender pays" would kill spam, too

...and then I realised it would kill mailing lists, too.

Then again, it might be made to work if, instead of the government taxing every outgoing mail spool, ISPs charged other ISPs for the privilege of sending mail to their users. That is, when [e-mail] sends a mail to [e-mail], AOL has to pay Hotmail 1/10 cent, or however much the "tax" is set at. These charges would be aggregated, so there would be one monthly bill instead of trillions of nano-payments. Your ISP subscription could include, say, 1000 free emails per month, or 12,000 per year.

I would expect that for normal email traffic, the amount flowing in each direction would be about equal. When someone starts spamming, though, their ISP is slapped with large invoices. If the ISP has any sense, they pass those invoices on to the spammer. If the invoices aren't paid, the ISP that sent them refuses any traffic from those IP blocks.

For spam that comes through open relays or proxies, invoice whoever runs the open machine, and let them worry about where it really came from. If they can find the spammer and recover the cost from him, great. If not, they'll have learned a valuable lesson about not leaving an unsecured box on the open Internet.

A scheme that requires all (or many) ISPs to change their behaviour would be difficult to get working, but easier than one that requires all (or many) email users to change. The biggest problem I foresee is that it's notoriously hard to extract money from a spammer. Still, if ISPs who are currently spam-friendly know that selling connectivity to a spammer will cost them a large amount of money, they might be more careful about whom they sign up.

Spammers don't use their own email boxes...

Considering that they don't use their own names, their own email accounts, SMTP servers or much of anything else that's tracable (there would be acts of violence if we could get our rightously indignated hands on 'em,) just who is this bozo proposing pay this tax?

Somebody buy 'm a clue.

Enforce the fraud laws, not TAXES!

This is where anti-spam legislation will lead us.

First we'll have the $0.00001 per email tax. It will fail, but we're told its failing because enforcement doesn't work when you don't know where the SMTP servers are. Which means that we'll have a law requiring SMTP server registration, enforced by the IRS and your ISP.

Forget to pay your SMTP tax when setting up your new box? Good news! The IRS can now search your hard disk (gotta know how much untaxed mail you sent) and then file tax liens against your bank account and your home.

When these don't work, we'll be told that the tax rate isn't high enough. So they'll raise it. And keep raising it. And then someone will figure out that it's a great way to put PCs in poor neighborhoods or some other "worthy" project.

Have I mentioned Ashcroft's take on SMTP registration?

Enforce the fraud laws. Arrest the people behind SPAM products. Ensnare the spammers as part of the conspiracy. That will solve the problem. Everything else just takes away our rights AND or money.

News from AD 2010

..and in other news, today a man was fined half a million dollars and jailed for five years for evading email taxes. IRS agents say that Joseph Smith of One Horse, Nebraska filed fraudulent SMTP logs and is suspected of having had encrypted tunnels to email servers in tax havens abroad. Reportedly, the prosecutor is also looking to charge him with evading the new web-page-hit tax, after his legal defense fund page was posted to the popular news site "Microsoft Slashdot".

Attorney general for life John Ashcroft commented "too late, assholes. In twenty oh three you let the camel get his nose in the tent, and now he's screwing your wife."

Interesting, but...

I run an email server. For the family. Total of four email addresses. My server directly delivers to other servers. How is this to be taxed?

Obviously, the computer SENDING the email pays the tax. But this means that some form of compliance checking will have to be put into place. Which means a change to the email protocols. But, other countries may not comply. Of course, running an email service for sending may simply be declared illegal, forcing all emails through a centralized point. This solution also has its problems. I guess the tax revenue collected could be used to run the central email servers.

Ratboy

OK, here's the study

An email is a message in a well known format composed a sequence of TCP/IP packets, usually but not always sent via a port 25 socket on an SMTP server, and usually but not always retrieved from a POP3 or IMAP server.

As the expressed intent is not to to punish recipients, the notion of taxing retrieval of emails is dismissed out of hand. Only the sending and relaying will be considered.

An SMTP server can be configured to handle email from anybody (an open relay) either deliberately or through incompetence or malice. Some SMTP server can be configured to require authorisation before handling email. Some SMTP servers are configured to only accept or send email to certain domains. Some SMTP servers are hidden (successfully or otherwise) on non-standard ports, behind firewalls, or are only accessible via (e.g.) SSH encrpyted connections. Some SMTP servers handle email only for a specific organisation, or for a specific machine.

SMTP servers are freely available for most computer platforms. Most linux distributions, for example, come with one or more SMTP servers as standard, there are several free SMTP servers avaiable for Windows, many email viruses contain their own SMTP servers to propagate themselves, or a simple SMTP server can be written in a few dozen lines of code or script.

Anyone connected to the internet anywhere in the world can set up an SMTP server and provide services to anyone they like. This may be against the acceptable use policy of their internet service provider (ISP), and their ISP may try to prevent it by technical means such as blocking the well known SMTP port 25, but there are ways to disguise the traffic or bypass these restrictions, including relaying to open SMTP servers on non standard ports and/or using SSH tunnels. Spammers can set up their own SMTP servers rather than using their ISP's servers, or can find and use open SMTP relays based anywhere in the world.

There is no practical way to oblige or enforce taxation on the administrator of an email server. Large US based ISPs could conceivably be taxed, but spammers commonly use open relays or their own SMTP servers. These can be based anywhere in the world. How will US legislation enforce taxation in Russia, for example? As a futher issue, at what level does email attract taxation? When it is being sent anywhere in the world? When it is being sent within the US? When it is sent from outside the US to servers inside the US? When it is sent within a subset of the internet, like a corporate or academic network, which can comprise tens of thousands of users? At the individual machine level?

Email is relayed across SMTP servers. In theory, it would be possible to tax the receiving SMTP servers of US based, large corporate ISPs and have them bill the sender. In practice, ISPs would be unable to collect this, and would in any case have to have accounts for every possible sender. This would lead to them either: rejecting email from the vast majority of non-US ISPs and being rejected in turn, effectively cutting the US off from the email network; or more likely, passing the costs on to the US based individual recipient either directly or indirectly.

In summary, Senator Dayton, the only practical way to keep the internet safe for Americans is to wall off part of it and declare a Fortress USA.

Any ISP who wanted to do that could do it right now. AOL could do it tomorrow. They have, for example, repeatedly experimented with rejecting email that appears to come from SMTP servers that don't appear to match the registered SMTP servers (well, their IP addresses) for the apparent sender's domain name. The reason why I repeat "apparent" is that these factors can be faked by malicious spammers, but that they catch out many legitimate senders, to the point where this policy has been unenforcable.

Thank you, Senator Dayton, for your interest in these matters, and for taking the time to suggest a superficial knee jerk solution that would wreck the internet as

Unnecessary coupling. "Fee" shouldn't imply "Tax"

It's clear that if the sender of an email suffered a cost above just paying for the computer and bandwidth, the problem of spam would be mostly eliminated. A fee of even just $0.00005 would cancel out the profits from the typical spam business plan.

But, also clear is that a government mandated tax would be absolutely the wrong way to impose this cost.

If a citizen wants to setup his email client so that all messages from strangers are deleted unless accompanied by a $5.00 paypal donation, that's his business! "Pay for email" can be implemented without government help. If we ever get a functioning micropayment system so that transactions of less than $0.05 can be cheaply exchanged, then it's quite probable that big ISPs (starting with AOL) will let their users elect to block all non-whitelisted emails unless the sender paid a minor fee to compensate for time wasted reading.

If the question is: "Should email require a stamp-like payment?", the answer is maybe.
But "Should the government tax email?", no.

If consumers decide that per-email fees are a fair price for eliminating spam, then private enterprise can provide it without state meddling. Pay-email poses technical and administrative challenges, so it might not ever really work- but sticking the IRS in there would just strengthen the obstacles.

related idea: fee payable to recipient

Here's an idea that has been mentioned before, but merits a mention here. It's not clear how we would "get there from here," but it's food for thought.

Imagine an e-mail system in which the sender of an e-mail would have to pay the recipient a fee specified by the recipient. The e-mail simply would not show up in the recipient's inbox unless the fee is paid.

You would be able to provide "keys" to regular correspondents, legitimate mailing lists, etc., that would allow them to reach your inbox without paying a fee. The keys would be revokable, in case they are abused or fall into the wrong hands.

It would be an expected courtesy, but not enforced, that legitimate e-mail that pays a fee would have the fee refunded once the recipient recognizes the mail as legitimate.

Now, if you're actively seeking e-mails from unknown senders -- for example, if you advertise a product or service and tell people to e-mail you for more information -- then you probably wouldn't charge a fee to reach your inbox. If you're a more typical user, you would set a small fee, probably just a few cents, so as not to deter legitimate mail.

A spammer, assuming he doesn't have keys to millions of inboxes, would need to pay tens of thousands of dollars in order to reach them all, assuming they each require a payment of a few cents.

This would not only deter spam but also compensate its victims. However, it would have little effect on legitimate e-mail.