Postfix/Exim sender address rewriting (was: Postfix ... ComCast port 587)

[Lloyd Kvam]

On Wed, 2009-01-21 at 13:06 -0500, Ben Scott wrote:
> At least one person is confused here (me); possibly everybody.  :-)
> 
>   The scenario here (for me, and I believe the OP) is rewriting email
> addresses, not masquerading as a different host.
> 
>   Two have people suggested a config directive for Postfix:
> 
> 	myhostname = foo.example.com
> 
>   Now, I don't know Postfix, but I'm guessing that sets the hostname.
> :)  Since confusion over hostname and reverse-path was seen earlier,
> and is being seen here, I am going to spell things out step-by-step,
> in the hope of establishing mutual understanding.  :)

I've got:

myorigin = venix.com

The commented section of main.cf:
# SENDING MAIL
#
# The myorigin parameter specifies the domain that locally-posted
# mail appears to come from. The default is to append $myhostname,
# which is fine for small sites.  If you run a domain with multiple
# machines, you should (1) change this to $mydomain and (2) set up
# a domain-wide alias database that aliases each user to
# user at that.users.mailhost.
#
# For the sake of consistency between sender and recipient addresses,
# myorigin also specifies the default domain name that is appended
# to recipient addresses that have no @domain part.
#
#myorigin = $myhostname
#myorigin = $mydomain
myorigin = venix.com

Obviously you will want a different domain than venix.com.
> 
(snipped)
>   Example: My PC's hostname is <blackfire>.  I've got an /etc/hosts
> entry that will cause that to canonicalizize to
> <blackfire.local.bscott>.  So when my MTA (Sendmail) talks to Comcast,
> it HELO's as <blackfire.local.bscott>.
> 
>   My user account is <bscott>.  By default, my MTA would build my
> email address as <bscott at blackfire.local.bscott>.  That's obviously
> invalid outside my LAN.
> 
>   My public email address right now is <dragonhawk at gmail.com>.
> Changing my MTA's idea of my hostname to <gmail.com> would yield
> <bscott at gmail.com>, which doesn't help.
> 
>   I could rename my account.  But then if I wanted to switch to my
> Comcast address (which is <bscott192 at comcast.net>), I'd have to change
> everything again.  If I get my vanity domain working again, I'd have
> to rename my local account to "public", so my default email address
> would be <public at dragonhawk.org>.  My account name is used in config
> files all over my PCs; this would be a mess.
> 
>   So, what I want to do is tell my MTA to rewrite <bscott> and some
> variants to <dragonhawk at gmail.com>.  My MTA can keep on using
> <blackfire.local.bscott> for its hostname, but I want it to modify the
> reverse-path.
> 
>   Do do that, I add an entry to the Sendmail /etc/mail/genericstable,
> which looks like this:
> 
> 	bscott	dragonhawk at gmail.com
> 
>   For a hypothetical other user on my PC, I could add:
> 
> 	bobama	president at whitehouse.gov
> 

Using myorigin is too simplistic for your example.  It would simply
rewrite bscott to bscott at venix.com

>   The scenario here (for me, and the OP) is rewriting email addresses,
> not masquerading as a different host.  :)
> 
>   So, {can, how would} this be done in Postfix and/or Exim?
> 
> -- Ben
> _______________________________________________
> gnhlug-discuss mailing list
> gnhlug-discuss at mail.gnhlug.org
> http://mail.gnhlug.org/mailman/listinfo/gnhlug-discuss/
-- 
Lloyd Kvam
Venix Corp
DLSLUG/GNHLUG library
http://dlslug.org/library.html
http://www.librarything.com/catalog/dlslug
http://www.librarything.com/rsshtml/recent/dlslug
http://www.librarything.com/rss/recent/dlslug