If you have any comments/suggestions/etc, they should be sent to the 
rules main author (Argus) at 7152...@compuserve.com.
Neil Ford. (nf...@cix.compulink.co.uk)
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Argus's draft rules for Play-By-Mail play of Magic: the
Gathering, v0.2. These may be distributed freely as long as
credit is given.
 
First, there are several problems that I can't find solutions
for:
 
A) Deck validation
 
I know of no practical way to verify that each player has the
cards and quantities they use in the game.
 
B) Revealing deck data
 
Whoever verifies the play will end up knowing exactly what was in
the deck and exactly what each player held in their hand when
they played.  In the minimalist approach, each player finds out
this information about the other after the game is over.
 
C) Counting cards
 
If the players choose their own decks, they can know exactly what
is left in their library at any time.  It is a general
characteristic of PBM games that the players can not be prevented
from keeping any records they want.
 
D) Chaos Orb
 
The Contract from Below and a couple other cards are marked not
to be used without ante.  I suspect that the Chaos Orb will need
a similar designation for PBM.  Attempts to get players to
specify their layouts would yield lots of 106mm gaps.
 
With these problems understood, the variations on procedures can
be defined.
 
1) The Library
 
Before play, each player announces how large their deck is and
secretly numbers them.  The numbered lists of cards are then sent
to some secure storage area. This can be a neutral party who acts
as a GM, or (in the minimalist approach) it can be a write-only
archive that both players examine afterwards to check for
cheating.  Then, whenever cards need to be taken from the "top"
of a deck for ante, dealing, drawing, or any other purpose, the
opponent selects a number from those not already chosen and tells
it to the other player.  (For Demonic Tutor or anything else
where a player chooses cards, the player just looks up the number
on their own list and tells the opponent what was used.)  If a
number already used is chosen, the player should simply drop to
the next unused card on the list and so inform his opponent.
 
The recommended approach for numbering is to shuffle the deck and
then take the numbers from the sequence they end up in.  The
recommended approach for choosing numbers for the opponent's
cards is to choose randomly from what is left (for example, by
drawing numbers from a hat).  If either chooses to use the
recommended approach (or something equivalent), the result will
be random.  Second-guessing the other player's choice of numbers
only has an effect if both players try to do it; such a mutual
agreement can be considered a house rule.
 
There are other cases in which information would need to be sent
to the referee/archive (summonings under the influence of
Illusionary Mask and the new deck sequence after a
Timetwister(?)).  They just require letting the archive format be
general.
 
2) Play of cards.
 
The players take turns sending messages back and forth specifying
what they play (or use) or passing.  Two passes in a row
terminate activity.  When the casting of a spell is announced,
two passes indicate the end of fast effects and the spell is then
considered cast (or not).  Any Interrupt would also need two
passes before completion.  When the actions are finished for a
turn, two passes mark the end of the turn.  If the player who
sends the second pass is the one with the responibility to act
next, the next action can be put in the same message as the pass.
 
A player may announce several actions in one message, but the
other player may play an action for any point within the message. 
The rest of the message would then be ignored; actions after the
first would have an implicit "if you do nothing" clause.  This
would most typically be used for tapping lands and casting a
spell, or for casting an Interrupt on one's own spell.  In the
case of nested Interrupts, several passes could be announced the
same way.
 
Timing conflicts can be resolved by the normal M:tG rules.
 
Attacks would work well with the sequence in the FAQ list, with
two passes marking the end of each round of fast effects.
 
Example:
 
R has four Swamps in play, one of which has Psychic Venom on it
and one of which is tapped.  D has a Plains (tapped), an Island,
two Mountains (both tapped), and a Basalt Monolith in play.  It
is R's turn.
 
R: Tap the two remaining unvenomed Swamps.  Cast Sinkhole on your
Plains.
 
D: Tap the Island and the Basalt Monolith.  Cast Power Sink
(Interrupt) with X=3.  "Remember that you have to try to feed it
even if you don't have enough."
 
R: Tap the last Swamp, losing 2 life.  Cast Dark Ritual
(Interrupt) and use the 3 mana to feed the Power Sink.
 
D: Pass.  "Ouch."
 
R: Pass.  [Dark Ritual completed.]  "Are you going to do anything
else to the Sinkhole?  If not, I won't."
 
D: "No."  Pass.  [Power Sink completed.]  [Sinkhole completed.]
(removes Plains to graveyard)
 
R: Pass.
 
D: Pass.  [End of R's turn.]  (R has fewer than seven cards and
neither has damaged creatures, so D proceeds to untap his lands.)
 
The quantity of passes could be a problem.  It reflects the
number of times that a player might play a card but can't or
won't.  For example, if D had had the right lands and cards, his
first pass could instead have been a Chaoslace and Blue Elemental
Blast cast on the Dark Ritual.  The first draft of the example
actually had three more passes as the spells were completed.
 
3) Ante.
 
Selection of ante is done at the beginning with the normal
card-drawing procedure.
 
The PBM version can be played with virtual decks, in which case
the players just update their respective lists afterwards.
 
If the players want to risk their physical cards, they will need
to work out the details of transfer before play begins.  Handing
them to a mutual friend who will be travelling between them or
hanging on to them until some physical meeting are the least
expensive ways.  Mail can be used, especially if a number of
cards will be transfered.  In the U.S., a twenty-nine cent stamp
is enough for about fifteen cards in an envelope.  (The standard
procedure for trades by mail should be listed here once I find
out what it is.)
4) Conventions.
When listing the layout for the benefit of the opponent, the
symbols "+" and "-" should be used to denote untapped and tapped
cards, respectively.
 
Argus (with input from Storm and Shadowcat)