🚀 go-pugleaf

Julian Bradfield  <jcb@inf.ed.ac.uk> wrote:
>On 2011-02-15, Kurt Hackenberg <kh@pnnnnx.kom> wrote:
>> Julian Bradfield  <jcb@inf.ed.ac.uk> wrote:
>>>A sensible format would use content-length...
>> No, because content-length is number of bytes in the message body,
>> which includes end-of-line characters and such, so it varies across
>> systems.  If you move the file from one system to another, it breaks.
>
>Er, it's up to the MTA/MUA to maintain the Content-Length correctly if
>they do anything other than make a perfect binary copy.
>The format already exists, and VM already supports it.

I was talking about moving the file outside of the mail software.
Say, with FTP or similar.  Useful for import/export, archive, etc.

>> I've had an idea to use the dot-stuffing algorithm used by SMTP: a
>> message is terminated by a line containing nothing but '.'; any such
>> line in the message gets another '.' added at the front.
>
>You also need to stuff any line containing only dots, of course.

That's what I said.

>That's what From-stuffing is like, and it's evil. It should not be
>necessary to mangle a message in order to store it.

No, SMTP's dot-stuffing is reversible.  The original message is easily
restored.  Every mail message sent across the Internet goes through
this: the sending MTA dot-stuffs the message, the receiver undoes it.

From-stuffing is not reversible, because a message line starting with
">From " doesn't get a second '>', so it becomes impossible to know
whether the '>' was there originally or added later.  That information
is lost.  That's the evil.

SMTP's algorithm, from RFC 5321 (descendant of 821), section 4.5.2:

   o  Before sending a line of mail text, the SMTP client checks the
      first character of the line.  If it is a period, one additional
      period is inserted at the beginning of the line.

   o  When a line of mail text is received by the SMTP server, it checks
      the line.  If the line is composed of a single period, it is
      treated as the end of mail indicator.  If the first character is a
      period and there are other characters on the line, the first
      character is deleted.