[nSLUG] dot issue seems to be a mailing list bug

Donald Teed donald.teed at gmail.com
Wed Nov 30 22:03:15 AST 2005

On 11/30/05, Jeff Warnica <jeff at coherentnetworksolutions.com> wrote:
> On Wed, 2005-11-30 at 20:02 -0400, Donald Teed wrote:
> >
> > The SMTP server at Gmail, and my own postfix, can email a message
> > containing
> > a line starting with the dot and by itself (and a blank line before
> > and after)
> > and continue sending lines after that.
> >
> Actually telneting to nslug.ns.ca:25 and trying this out seems to
> discount this theory. Likely postfix or gmail is doing something to the
> message before it gets to whatever nslug is running.

Errr, postfix is an SMTP server, so same difference.  I meant
that email passing through it is unscathed when using the
dot by itself.

Anyway you found the answer in the RFC, as Robert McKay
also mentioned:

> >    -  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.
> >
> >    -  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.

To put it simply:
The first part of the job is done by your mail client.  If you
enter . by itself, it sends a line of '..' .  The receiving SMTP
server reads it, it removes the first dot.

I do remember receiving emails with ">From" showing where
I had input "From", but I've also tested that, and at least
with pine and postfix, this is no longer a problem.  Perhaps
the RFC mentions a solution similar to the dot problem.


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