Anonymous remailers are great tools.
They provide numerous useful applications, sometimes invaluable to public liberties.
Like any efficient tool, they can be diverted to unwanted purposes.
(Cf: Why use Anonymous Remailers?).

It is my belief that advantages outweight inconveniences.
I believe it so much that I spend bandwidth, processor activity and free time on it.
(Cf: A few words from the Admin / Webmaster).

Some kinds of abuse can be easily fought, some cannot.
Thank you for using the address Frog-Abuse only if your problem can be handled.

If you are sure you will never want to receive any mail coming from remailer 'Frog',
you may ask your E-mail @ to be blocked
1) use the E-mail account you want to be blocked, write to Frog-Abuse
2) you will get an answer to that @, asking for confirmation
      that mail will include a passphrase (to avoid possible impersonation)
3) send back the confirmation and do not forget the passphrase
4) your account will be blocked for one year:
       any mail sent to your @ will be deleted by the remailer
       any mail coming from your @ will be deleted by the remailer
NB
No questions asked (ie you do not need to supply copies of harassing mail).
If it is a temporary annoyance, would not a mere filter on your mail client be enough?
You got to send one message from each @ to be protected.
Do not forget mandatory passphrase.
Similar procedure exists for other remailers.
Do not hesitate to broadcast this info.

If you are sure that none of your end-users will ever want to receive any mail from remailer 'Frog',
and if you are in charge of the domain(s).
you may ask your domain(s) to be blocked.
1) write to Frog-Abuse and include the Internic references for your domain(s).
2) you will get an answer to the @ of the person in charge of the domain(s), after a WHOIS to confirm.
      that mail will include a passphrase (to avoid possible impersonation)
3) send back the confirmation and do not forget the passphrase
4) your domain(s) will be blocked for one year:
       any mail sent to those @ will be deleted by the remailer
       any mail coming from those @ will be deleted by the remailer
NB
No questions asked (ie you do not need to supply copies of harassing mail).
If it is a temporary annoyance, would not a mere filter on your mail server be enough?
Do not forget mandatory passphrase.
Similar procedure exists for other remailers.
Do not hesitate to broadcast this info.

If somedy posts messages of dubious value and tries to make people believe you authored them:
Both mails and posts processed by 'Frog' bear 4 lines of comments
  clearly stating that the messages have been remailed by 'Frog' and were not directly issued by you.
It is easy to point that out, even to a person who is not ès-Headers-litterate.
You get a better protection than if your agressor had used a 'throwaway' free account.
If your agressor is stubborn, you might consider the advice in the comments.
Systematically authenticate your posts through PGP...
It is now possible to ask that your @ in the 'From:' field of an outbound message would block it.
That new functionnality is just a by-product of a mechanism aimed at reducing message loss.
I accept to block only authenticated @ , no screen names nor real names.
1) Write to Frog-Abuse
2) you will get an answer to that @, asking for confirmation
      that mail will include a passphrase (to avoid possible impersonation)
3) send back the confirmation and do not forget the passphrase
4) your account will be protected for one year:
To tell the truth, I am moderately confident in that filter's utility.
Nothing prevents the impersonator from putting your @ in the message's body.
Unfortunately, that hint might be enough for you to be targeted
by those uneducated and agressive enough to be fooled and react at that kind of messages.
But, in the first place, why the heck did you broadcast such private information as your @ on Usenet???!!!

Creating a few thousands  PGP-encrypted messages would not be cost-effective to a 'real' professional spammer.
For sure, it is somebody trying to give anonymous remailers a bad name.
I would be personnally delighted to find out about the author and expose his name.
I would even consider suing for damage if posts were illegal (...)
It is now possible to ask for such messages to be filtered, against their Subject.
Write to Frog-Abuse. (Don't expect miracles, though..., as my time is limited and this is a lost war)

Some NG are dedicated to that type of post (alt.anonymous.messages).
Besides a technical mistake which would be quickly corrected,
a sure bet is that somebody is trying to give anonymous remailers a bad name.
I would be personnally delighted to find out about the author and expose his name,
This kind of messages generally bears a fixed, unique 'Subject:'. Filter against'Subject:', not against 'Origin:'.
It is now possible to ask for such messages to be filtered, against their Subject.
Write to Frog-Abuse. (Don't expect miracles, though..., as my time is limited and this is a lost war)

A BI calculation should suppress the messages in excess.
Using anonymous remailers does not make authors better or more diversified...
It is now possible to ask for such messages to be filtered, against their Subject.
Write to Frog-Abuse. (Don't expect miracles, though..., as my time is limited and this is a lost war)

I do not speak more than 6 languages and I am not interested in all the 70.000 NG I have access to,
not even their charters.
Besides, I feel no vocation in censorship, and I do not read what emerges from the remailer.
In addition, remailers are dedicated to allow expression from minorities, even extremist views.
(Cf: F.A.Q. (Frequently Asked Questions) about most serious matters.)
If your case is strong, convince the trouble-maker.
If not, ignore him: he will get bored. Do Not Feed the Troll.
On the other hand, in case of persistant and obvious annoyance,
one cannot emphasize too much the use of individual *filters*, available on all recent newsreaders.
That feature will be quite efficient, because most trolls and trouble-makers *love* to sign their deeds,
their are craving for any kind of notoriety, whatever dubious..
And broadcast the information *by private mail* to NewB tempted to react impulsively to the loud-mouthed.
It is now possible to ask for such messages to be filtered, against their 'From:'
Write to Frog-Abuse. (Similar possibilities do exist too at the m2news gateways level)
      But I must warn there is little chance I cave in to such requests, except most serious cases.
      'Troll' is part of Usenet culture, free speech got its rights..
And of course there is no way I would block a NG because of unpleasant messages:
it would be all too easy for a remailer-hater to have all NG shut down on those grounds, the one after the other.
And to end with, do not forget:
the best filter is your brains:
  an unpleasant message can be evaluated within a fraction of a second
  it takes a click from the mouse to go on for the next one, more interesting.

Some self-righteous loud-mouthed individuals apparently took the vows to complain about everything on Usenet.
I consider this to be a psychiatric disorder and abuse.
In case of harassment against my 'Abuse' @ by such individuals,
.. I will not hesitate to fill a formal complaint against them at their own ISP
.. Harasser will find himself *much* more involved than he expected in Frog's operations