Re: [Exim] Dots in local parts

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Author: Matthew Byng-Maddick
Date:  
To: exim-users
Subject: Re: [Exim] Dots in local parts
On Fri, Jun 14, 2002 at 12:20:38PM +0100, Nigel Metheringham wrote:
> On Fri, 2002-06-14 at 12:11, Matthew Byng-Maddick wrote:
> > It does seem sensible to restrict "^\..*" due to traditional mappings
> > of email addresses to files on disk, and the traditions of dotfiles,
> > which are "hidden" from a normal list, and contain configuration or
> > preference information.
> I'd go further than that - in general I'd expect local_parts to match
>     ^[a-zA-Z0-9][a-zA-Z0-9+:._-]*$
> ie leading alphanumeric, followed by alphanumerics and a few special
> characters.  Definitely avoiding things like /\ shell meta chars etc.


interesting you should say this, because on one machine I maintain, where
I use a combination of qmail and ezmlm (best not to ask... :-), I've been
having problems with Hotmai Lusers and Yahoo! Users being unable to read,
and Hotmail and Yahoo! unable to work out what a "local-part" in an email
address actually looks like. The problem is that ezmlm, by default, uses
confirmation addresses of the form:
<listname>-<blurb>-<target local-part>=<target domain-part>@<list domain>
                                       ----------------------------------


Of course, the bit that hotmail/yahoo interpret as an email address (and
therefore turn into a link) in their webmail is as marked above. Not
hugely useful, obviously. I'd agree with you about shell metachars,
though people being unaware can make life very difficult for software
that exists already. I'm actually surprised that hotmail and yahoo are
so broken, and I'm going to be using an `_' instead, for the bits I need,
but it does illustrate the problem with making your regex too restrictive.

In general, though, I'd probably agree, and if I hadn't been battling with
this problem in the recent past, I probably would have agreed to restrict
the default down as far as you. (though, of course, `:' isn't a valid
local-part character, because it's a list begin character)

We have standards so they can be broken?

MBM

--
Matthew Byng-Maddick         <mbm@???>           http://colondot.net/