Lines Beginning with "From" Dash-Escaped?

[John A. Martin]

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>>>>> "IK" == Ingo Klöcker
>>>>> "Re: Lines Beginning with "From" Dash-Escaped?"
>>>>>  Sat, 28 Apr 2001 11:42:10 +0200

    >> Can anyone expand on the reasons why PGP and GPG use the
    >> dash-escape in this manner, aside from what is written in the
    >> RFC?

    IK> I found this in the NEWS:

    IK> Noteworthy changes in version 0.9.0
    IK> ----------------------------------- [snip]
    IK> * New option --escape-from-lines to "dash-escape" "From "
    IK>       lines to
    IK> 	prevent mailers to change them to ">From ".  This is
    IK> 	not enabled by default because it is not in compliance
    IK> 	with rfc2440 - however, you should turn it on.

    IK> Reason: If a MUA uses the mailbox format, i.e. a simple text
    IK> file where all messages are stored one after the other a line
    IK> starting with "From " is used to mark the start of the next
    IK> message. There are a lot of MUAs which use the mailbox format,
    IK> for example Netscape Messenger, KMail and also Pine and Mutt.
    IK> Now if a line inside a message starts with "From " it will be
    IK> changed to ">From " by the MUA while receiving the mail. But
    IK> this additional ">" would break the signature. Therefore PGP
    IK> and GnuPG dash-escape the "From " if they clear-sign messages.

The crux of the matter is that many MTAs will escape leading
From-space during local delivery.

    IK> The reason why you never have seen a line beginning with
    IK> ">From " might be because the MUA automatically removes the
    IK> ">" before displaying the mail. The ">" can only be found in
    IK> the mailbox file in which the message is stored.

Also, some local delivery agents are smart enough to only escape the
From-space if it is preceded by a blank line and the remainder of the
line "looks like" a mailbox delimiter.  Moreover, more and more mail
systems are being optioned not to use the Berkeley style mailbox that
uses a From-space line to delimit mail messages.

	jam

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