From: "James R. Marcus" on
Hi,
We send email to new users and frequently they give us false addresses or the address gets entered incorrectly. One example would be instead of aol.com the address gets entered as aol.cm. I would like to bounce invalid addresses quickly instead of retrying them for days on end. Its my understanding yahoo.com, hotmail.com etc change our domain's Sender Score based on retrying non existent addresses i.e. usernames. I figured this might be a common scenario and read the FAQ on Kyle Dent's site. I don't want to bounce emails that have been deferred.

I would like to hear if other people have implemented similar solutions?


Thanks,
James
From: /dev/rob0 on
On Sun, Jul 11, 2010 at 11:47:42AM -0400, James R. Marcus wrote:
> We send email to new users and frequently they give us false
> addresses or the address gets entered incorrectly. One example

"They give us false addresses" ... sounds like you need to do some
sort of verification in the place where they are giving you these
addresses. A web form? Off-topic here, of course.

> would be instead of aol.com the address gets entered as aol.cm. I

Not a good example, because this is not a problem.

aol.cm. 86400 IN MX 5 mx1.emailparking.com.

$ host mx1.emailparking.com.
;; connection timed out; no servers could be reached

> would like to bounce invalid addresses quickly instead of retrying
> them for days on end.

If the recipient domain does not resolve, do not accept that address
from your user. This could be tested in your web form. If you
accepted it anyway, it will stay in your queue until the first retry
attempt after $maximal_queue_lifetime.

If the recipient domain does resolve, but the address is not valid
there, they should reject you on your first attempt, and you have a
bounce for your bounce-handling code to deal with. Why are you
retrying after rejection?

If the recipient domain does resolve, but the address is not valid
there, but they reject you with temporary errors, there is nothing
you can do. It's THAT site which has the problem.

> Its my understanding yahoo.com, hotmail.com etc change our
> domain's Sender Score based on retrying non existent addresses
> i.e. usernames.

This might be so, but again, there is no reason why you should try
more than once. Is your Web form continuing to generate
confirmations?

> I figured this might be a common scenario and read the FAQ on Kyle
> Dent's site. I don't want to bounce emails that have been deferred.

Nope, this is not a common scenario. If you have a real-world
problem, you should describe it better, and include relevant logs
with postconf -n output.
http://www.postfix.org/DEBUG_README.html#mail

One WAG included free of charge:
http://www.postfix.org/postconf.5.html#soft_bounce
Did you set "soft_bounce = yes"?

> I would like to hear if other people have implemented similar
> solutions?

It might be desirable to put commonly-misspelled domain names in a
transport(5) table, but so far that's not what you have talked about.
If that's what you want, Google has examples of that on this list's
archives.
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From: Ralf Hildebrandt on
* James R. Marcus <jmarcus(a)edhance.com>:
> Hi,

> We send email to new users and frequently they give us false addresses
> or the address gets entered incorrectly. One example would be instead
> of aol.com the address gets entered as aol.cm.

Yes, it happens.

> I would like to bounce invalid addresses quickly instead of retrying
> them for days on end.

All you can do in these cases is to add transport_maps entries for
those:

aol.cm error:User typoed aol.com

> Its my understanding yahoo.com, hotmail.com etc change our domain's
> Sender Score based on retrying non existent addresses i.e. usernames.

It never reaches those, it goes elsewhere. Because of the typo.

> I figured this might be a common scenario and read the FAQ on Kyle
> Dent's site. I don't want to bounce emails that have been deferred.

But it has been deferred, just like you write "instead of retrying
them for days on end." aka "deferred!

--
Ralf Hildebrandt
Geschäftsbereich IT | Abteilung Netzwerk
Charité - Universitätsmedizin Berlin
Campus Benjamin Franklin
Hindenburgdamm 30 | D-12203 Berlin
Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962
ralf.hildebrandt(a)charite.de | http://www.charite.de