Regular Expressions and RFC 822

[Tim Roberts]

"alex gigh" <cogs2002 at hotmail.com> wrote:
>
>I am trying to write a mail server in Python and I found out that I can use 
>regular expressions and then grouping:
>
>"For example, an RFC-822 header line is divided into a header name and a 
>value, separated by a ":". This can be handled by writing a regular 
>expression which matches an entire header line, and has one group which 
>matches the header name, and another group which matches the header's value. 
>"

That's not exactly true.  RFC-822 header lines are often continued onto
multiple lines.  A line following a header that starts with whitespace is
automatically a continuation of the previous line:

Subject: This is a rather unusual
    but perfectly legal
    subject line that could not
    be easily parsed with a simple regular
    expression.
To:  "Joe Cool"
     <jcool at snoopy.com>,
     "Charlie Brown"
     <kicker at snoopy.com>

When you say you are writing a mail server, what do you really mean?  Are
you writing a mail CLIENT, or are you actually writing a mail transfer
agent like sendmail?
--
- Tim Roberts, timr at probo.com
  Providenza & Boekelheide, Inc.