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testing email deliverability...

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  testing email deliverability... The Natural Philosopher <tnp@invalid.invalid> - 2014-06-05 01:48 +0100
    Re: testing email deliverability... Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2014-06-04 18:40 -0700
    Re: testing email deliverability... "Tony Marston" <TonyMarston@hotmail.com> - 2014-06-05 03:47 +0100
      Re: testing email deliverability... Eli the Bearded <*@eli.users.panix.com> - 2014-06-05 04:53 +0000
        Re: testing email deliverability... Richard Kettlewell <rjk@greenend.org.uk> - 2014-06-05 09:13 +0100
          Re: testing email deliverability... Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2014-06-05 08:05 -0700
        Re: testing email deliverability... Arno Welzel <usenet@arnowelzel.de> - 2014-06-09 11:30 +0200
          Re: testing email deliverability... Eli the Bearded <*@eli.users.panix.com> - 2014-06-09 23:08 +0000
            Re: testing email deliverability... Arno Welzel <usenet@arnowelzel.de> - 2014-06-10 11:08 +0200
    Re: testing email deliverability... Sam <sam@email-scan.com> - 2014-06-04 22:04 -0500
      Re: testing email deliverability... Jerry Stuckle <jstucklex@attglobal.net> - 2014-06-04 23:27 -0400
      Re: testing email deliverability... The Natural Philosopher <tnp@invalid.invalid> - 2014-06-05 05:37 +0100
        Re: testing email deliverability... Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2014-06-04 21:55 -0700
        Re: testing email deliverability... Chuck Anderson <cycletourist@invalid.invalid> - 2014-06-05 21:36 -0600
          Re: testing email deliverability... Jerry Stuckle <jstucklex@attglobal.net> - 2014-06-06 09:41 -0400
            Re: testing email deliverability... Denis McMahon <denismfmcmahon@gmail.com> - 2014-06-06 14:37 +0000
              Re: testing email deliverability... The Natural Philosopher <tnp@invalid.invalid> - 2014-06-06 16:46 +0100
                Re: testing email deliverability... Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2014-06-06 10:39 -0700
    Re: testing email deliverability... Jerry Stuckle <jstucklex@attglobal.net> - 2014-06-04 23:05 -0400
    Re: testing email deliverability... "AvdB" <nomail@example.invalid> - 2014-06-05 12:59 +0200
      Re: testing email deliverability... The Natural Philosopher <tnp@invalid.invalid> - 2014-06-05 13:51 +0100
    Re: testing email deliverability... Adrienne Boswell <arbpen@yahoo.com> - 2014-06-05 18:39 +0000
      Re: testing email deliverability... Eli the Bearded <*@eli.users.panix.com> - 2014-06-05 20:46 +0000
        Re: testing email deliverability... Keith Keller <kkeller-usenet@wombat.san-francisco.ca.us> - 2014-06-05 14:41 -0700
        Re: testing email deliverability... Adrienne Boswell <arbpen@yahoo.com> - 2014-06-05 22:21 +0000
    Re: testing email deliverability... James Moe <jimoeDESPAM@sohnen-moe.com> - 2014-06-05 13:14 -0700
    Re: testing email deliverability... Arno Welzel <usenet@arnowelzel.de> - 2014-06-06 14:11 +0200
    Re: testing email deliverability... Chris Davies <chris-usenet@roaima.co.uk> - 2014-06-09 13:53 +0100

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#13781 — testing email deliverability...

I have web contact pages which are used by anyone to send enquiries.

I want to make sure that anyone using them has a valid reply address set 
in a web form BEFORE I forward the message on to the site administrators.


Mailer is exim, and that's currently but not necessarily invoked by the 
php mail() function.


what I want is a function like

is_valid_mail("user12345@gmail.com")

that will return true or false if gmail accepts the user as known (yes 
the spam is always @gmail.com) WITHOUT having to write a dns mx lookup, 
then connect to socket 25 and etc etc etc..

exim -bt tells me if the domain is valid, but not the user.

I am not particular how its achieved - anything can be merged into the 
existing code.

anyone done this?


-- 
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to 
lead are elected by the least capable of producing, and where the 
members of society least likely to sustain themselves or succeed, are 
rewarded with goods and services paid for by the confiscated wealth of a 
diminishing number of producers.

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#13782

["Followup-To:" header set to comp.os.linux.misc.]

On 2014-06-05, The Natural Philosopher <tnp@invalid.invalid> wrote:
>
> I want to make sure that anyone using them has a valid reply address set 
> in a web form BEFORE I forward the message on to the site administrators.

There is absolutely no way to do this for arbitrary domains.  Some
MXs will accept all mail addressed to it, then decide later how to
handle the message (discard, bounce, deliver).

> that will return true or false if gmail accepts the user as known (yes 
> the spam is always @gmail.com) WITHOUT having to write a dns mx lookup, 
> then connect to socket 25 and etc etc etc..

It's not even possible (for an arbitrary domain) *with* doing an MX
lookup and connecting to port 25.  It will be possible for some MXs but
not all, and there's no way of determining ahead of time whether a
domain will do this for you or not.  This is why many sites require
separate confirmation by sending email to the target with a link that
verifies that the recipient actually received the mail.

--keith

-- 
kkeller-usenet@wombat.san-francisco.ca.us
(try just my userid to email me)
AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt
see X- headers for PGP signature information

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#13783

"The Natural Philosopher"  wrote in message 
news:lmoeok$5v6$1@news.albasani.net...
>
>I have web contact pages which are used by anyone to send enquiries.
>
>I want to make sure that anyone using them has a valid reply address set in 
>a web form BEFORE I forward the message on to the site administrators.
>
>
>Mailer is exim, and that's currently but not necessarily invoked by the php 
>mail() function.
>
>
>what I want is a function like
>
>is_valid_mail("user12345@gmail.com")
>
>that will return true or false if gmail accepts the user as known (yes the 
>spam is always @gmail.com) WITHOUT having to write a dns mx lookup, then 
>connect to socket 25 and etc etc etc..
>
>exim -bt tells me if the domain is valid, but not the user.
>
>I am not particular how its achieved - anything can be merged into the 
>existing code.
>
>anyone done this?
>
>
"The Natural Philosopher"  wrote in message 
news:lmoeok$5v6$1@news.albasani.net...
>
>I have web contact pages which are used by anyone to send enquiries.
>
>I want to make sure that anyone using them has a valid reply address set in 
>a web form BEFORE I forward the message on to the site administrators.
>
>
>Mailer is exim, and that's currently but not necessarily invoked by the php 
>mail() function.
>
>
>what I want is a function like
>
>is_valid_mail("user12345@gmail.com")
>
>that will return true or false if gmail accepts the user as known (yes the 
>spam is always @gmail.com) WITHOUT having to write a dns mx lookup, then 
>connect to socket 25 and etc etc etc..
>
>exim -bt tells me if the domain is valid, but not the user.
>
>I am not particular how its achieved - anything can be merged into the 
>existing code.
>
>anyone done this?
>
>

You can use the filter_var() function at 
http://uk3.php.net/manual/en/function.filter-var.php to check that an email 
address is syntactically valid, but you cannot check that an email exists 
without sending an email and getting a response back.

-- 
Tony Marston

http://www.tonymarston.net
http://www.radicore.org 

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#13788

In comp.os.linux.misc, Tony Marston <TonyMarston@hotmail.com> wrote:
> "The Natural Philosopher"  wrote:
>> I want to make sure that anyone using them has a valid reply address set in 
>> a web form BEFORE I forward the message on to the site administrators.

I'd like to verify that the lottery number is going to win before I buy the
ticket. Unfortunely I don't think either of us is going to be happy.

>> is_valid_mail("user12345@gmail.com")

Did you think that you are the first person to want this? Think how useful
it would be for spammers to find new email addresses before sending email!

> You can use the filter_var() function at 
> http://uk3.php.net/manual/en/function.filter-var.php to check that an email 
> address is syntactically valid, but you cannot check that an email exists 
> without sending an email and getting a response back.

I have NEVER seen a "syntactically valid" check that really works. The
comments on that page list many valid addresses that don't work. (And
many validators wrongly think I post from an invalid address, but it's
syntactically valid and a working mail alias.)

Elijah
------
and some "syntactically invalid" addresses work well in practice

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#13790

Eli the Bearded <*@eli.users.panix.com> writes:
> Tony Marston <TonyMarston@hotmail.com> wrote:
>>> is_valid_mail("user12345@gmail.com")
>
> Did you think that you are the first person to want this? Think how useful
> it would be for spammers to find new email addresses before sending email!

No use at all.  Spammers use stolen resources, so spam sent to
undeliverable addresses doesn’t cost them anything.

-- 
http://www.greenend.org.uk/rjk/

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#13793

["Followup-To:" header set to comp.os.linux.misc.]
On 2014-06-05, Richard Kettlewell <rjk@greenend.org.uk> wrote:
> Eli the Bearded <*@eli.users.panix.com> writes:
>> Tony Marston <TonyMarston@hotmail.com> wrote:
>>>> is_valid_mail("user12345@gmail.com")
>>
>> Did you think that you are the first person to want this? Think how useful
>> it would be for spammers to find new email addresses before sending email!
>
> No use at all.  Spammers use stolen resources, so spam sent to
> undeliverable addresses doesn???t cost them anything.

If they had a list of valid addresses they'd get their spam sent out
faster.  I strongly suspect they'd use such a resource if it existed.

--keith

-- 
kkeller-usenet@wombat.san-francisco.ca.us
(try just my userid to email me)
AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt
see X- headers for PGP signature information

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#13806

Eli the Bearded, 2014-06-05 06:53:

> In comp.os.linux.misc, Tony Marston <TonyMarston@hotmail.com> wrote:
>> "The Natural Philosopher"  wrote:
>>> I want to make sure that anyone using them has a valid reply address set in 
>>> a web form BEFORE I forward the message on to the site administrators.
> 
> I'd like to verify that the lottery number is going to win before I buy the
> ticket. Unfortunely I don't think either of us is going to be happy.
> 
>>> is_valid_mail("user12345@gmail.com")
> 
> Did you think that you are the first person to want this? Think how useful
> it would be for spammers to find new email addresses before sending email!
> 
>> You can use the filter_var() function at 
>> http://uk3.php.net/manual/en/function.filter-var.php to check that an email 
>> address is syntactically valid, but you cannot check that an email exists 
>> without sending an email and getting a response back.
> 
> I have NEVER seen a "syntactically valid" check that really works. The

This one should:

<http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html>



-- 
Arno Welzel
http://arnowelzel.de
http://de-rec-fahrrad.de
http://fahrradzukunft.de

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#13808

In comp.lang.php, Arno Welzel  <usenet@arnowelzel.de> wrote:
> Eli the Bearded, 2014-06-05 06:53:
> > I have NEVER seen a "syntactically valid" check that really works. The
> This one should:
> <http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html>

Did you actually read that page? Right there before the regexp is this
clear warning:

    The regular expression does not cope with comments in email
    addresses. The RFC allows comments to be arbitrarily nested. A
    single regular expression cannot cope with this. The Perl module
    pre-processes email addresses to remove comments before applying the
    mail regular expression. 

That particular test claims RFC822 awareness, but allows "å@å.å" which
does not pass the ASCII-ASCII-ASCII! RFC822 muster or RFC2822 muster,
even if it might be valid now depending on encoding (see RFC6532, which
first allowed non-ASCII email header values back in February 2012).

It also fails the too-rigid test: RFC822 does not allow email addresses
with a localpart that ends with a period, but periods are allowed
everywhere else in a localpart. This test enforces that rule, when real
world mailservers don't care all that much about <rfc822.@example.com>
not being RFC822 kosher.

Elijah
------
although a localpart of only periods is likely to fail

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#13809

Am 2014-06-10 01:08, schrieb Eli the Bearded:

> In comp.lang.php, Arno Welzel  <usenet@arnowelzel.de> wrote:
>> Eli the Bearded, 2014-06-05 06:53:
>>> I have NEVER seen a "syntactically valid" check that really works. The
>> This one should:
>> <http://www.ex-parrot.com/~pdw/Mail-RFC822-Address.html>
> 
> Did you actually read that page? Right there before the regexp is this
> clear warning:
> 
>     The regular expression does not cope with comments in email
>     addresses. The RFC allows comments to be arbitrarily nested. A
>     single regular expression cannot cope with this. The Perl module
>     pre-processes email addresses to remove comments before applying the
>     mail regular expression. 

Thanks for the clarification - I did not read that comment completely.



-- 
Arno Welzel
http://arnowelzel.de
http://de-rec-fahrrad.de
http://fahrradzukunft.de

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#13784

The Natural Philosopher writes:

> what I want is a function like
>
> is_valid_mail("user12345@gmail.com")
>
> that will return true or false if gmail accepts the user as known (yes the  
> spam is always @gmail.com) WITHOUT having to write a dns mx lookup, then  
> connect to socket 25 and etc etc etc..

I'm afraid that you will have to wait until someone invents a telepathic  
computer, that will be able to accomplishing such an amazinf feat.

Until then, unfortunately, a number of inconvenient laws of physics of this  
universe will prevent anyone from determining whether an email address is  
deliverable without looking up its MX server, and connecting to the MX  
server's port 25.

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#13786

On 6/4/2014 11:04 PM, Sam wrote:
> The Natural Philosopher writes:
>
>> what I want is a function like
>>
>> is_valid_mail("user12345@gmail.com")
>>
>> that will return true or false if gmail accepts the user as known (yes
>> the spam is always @gmail.com) WITHOUT having to write a dns mx
>> lookup, then connect to socket 25 and etc etc etc..
>
> I'm afraid that you will have to wait until someone invents a telepathic
> computer, that will be able to accomplishing such an amazinf feat.
>
> Until then, unfortunately, a number of inconvenient laws of physics of
> this universe will prevent anyone from determining whether an email
> address is deliverable without looking up its MX server, and connecting
> to the MX server's port 25.
>

Even then you don't know if the email address is valid.  May mail 
servers are set to accept and trash invalid email addresses.  This is 
because spammers would send emails to random accounts at an email 
address; if they didn't get a reject they knew the address was OK.


-- 
==================
Remove the "x" from my email address
Jerry Stuckle
jstucklex@attglobal.net
==================

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#13787

On 05/06/14 04:04, Sam wrote:
> The Natural Philosopher writes:
>
>> what I want is a function like
>>
>> is_valid_mail("user12345@gmail.com")
>>
>> that will return true or false if gmail accepts the user as known (yes
>> the spam is always @gmail.com) WITHOUT having to write a dns mx
>> lookup, then connect to socket 25 and etc etc etc..
>
> I'm afraid that you will have to wait until someone invents a telepathic
> computer, that will be able to accomplishing such an amazinf feat.
>
> Until then, unfortunately, a number of inconvenient laws of physics of
> this universe will prevent anyone from determining whether an email
> address is deliverable without looking up its MX server, and connecting
> to the MX server's port 25.
>
I meant without me having to write such code,, but it seems someone 
already hass..

http://www.tienhuis.nl/files/email_verify_source.php


-- 
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to 
lead are elected by the least capable of producing, and where the 
members of society least likely to sustain themselves or succeed, are 
rewarded with goods and services paid for by the confiscated wealth of a 
diminishing number of producers.

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#13789

["Followup-To:" header set to comp.os.linux.misc.]

On 2014-06-05, The Natural Philosopher <tnp@invalid.invalid> wrote:
>
> I meant without me having to write such code,, but it seems someone 
> already hass..
>
> http://www.tienhuis.nl/files/email_verify_source.php

As I and others have already stated, this method is not reliable in
general, as some MXs will accept all email for its domains whether
the destination address is valid or not, in order to defeat exactly this
sort of query (done by spammers, but what defeats them defeats this
too).

All this script will do is tell you whether the MX accepted the message.
It can never tell you whether the MX delivered it to a valid mailbox,
discarded it, or generated a bounce.

--keith

-- 
kkeller-usenet@wombat.san-francisco.ca.us
(try just my userid to email me)
AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt
see X- headers for PGP signature information

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#13799

The Natural Philosopher wrote:
> On 05/06/14 04:04, Sam wrote:
>> The Natural Philosopher writes:
>>
>>> what I want is a function like
>>>
>>> is_valid_mail("user12345@gmail.com")
>>>
>>> that will return true or false if gmail accepts the user as known (yes
>>> the spam is always @gmail.com) WITHOUT having to write a dns mx
>>> lookup, then connect to socket 25 and etc etc etc..
>>
>> I'm afraid that you will have to wait until someone invents a telepathic
>> computer, that will be able to accomplishing such an amazinf feat.
>>
>> Until then, unfortunately, a number of inconvenient laws of physics of
>> this universe will prevent anyone from determining whether an email
>> address is deliverable without looking up its MX server, and connecting
>> to the MX server's port 25.
>>
> I meant without me having to write such code,, but it seems someone 
> already hass..
>
> http://www.tienhuis.nl/files/email_verify_source.php

I feel I'm about to step into a giant pile of doo, but .... Some years 
back I used a Windows program from Analogx called listmaster pro to 
verify email addresses manually (it is designed to be used with large 
mail lists.  I never verified more than several at a time).  It always 
gave me correct positive and negative results.  It seems to me that, in 
general, an email address can be verified as a valid mailbox - or not.  
There are no guarantees, of course, but this program always gave me the 
correct result.

-- 
*****************************
 Chuck Anderson • Boulder, CO
  http://cycletourist.com
 Turn Off, Tune Out, Drop In
*****************************

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#13802

On 6/5/2014 11:36 PM, Chuck Anderson wrote:
> The Natural Philosopher wrote:
>> On 05/06/14 04:04, Sam wrote:
>>> The Natural Philosopher writes:
>>>
>>>> what I want is a function like
>>>>
>>>> is_valid_mail("user12345@gmail.com")
>>>>
>>>> that will return true or false if gmail accepts the user as known (yes
>>>> the spam is always @gmail.com) WITHOUT having to write a dns mx
>>>> lookup, then connect to socket 25 and etc etc etc..
>>>
>>> I'm afraid that you will have to wait until someone invents a telepathic
>>> computer, that will be able to accomplishing such an amazinf feat.
>>>
>>> Until then, unfortunately, a number of inconvenient laws of physics of
>>> this universe will prevent anyone from determining whether an email
>>> address is deliverable without looking up its MX server, and connecting
>>> to the MX server's port 25.
>>>
>> I meant without me having to write such code,, but it seems someone
>> already hass..
>>
>> http://www.tienhuis.nl/files/email_verify_source.php
>
> I feel I'm about to step into a giant pile of doo, but .... Some years
> back I used a Windows program from Analogx called listmaster pro to
> verify email addresses manually (it is designed to be used with large
> mail lists.  I never verified more than several at a time).  It always
> gave me correct positive and negative results.  It seems to me that, in
> general, an email address can be verified as a valid mailbox - or not.
> There are no guarantees, of course, but this program always gave me the
> correct result.
>

And how did it know?

For instance - I have three domains.  You can send and email to any 
address at any of the three.  But unless it's a valid address, the email 
ends up in /dev/null.


-- 
==================
Remove the "x" from my email address
Jerry Stuckle
jstucklex@attglobal.net
==================

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#13803

On Fri, 06 Jun 2014 09:41:05 -0400, Jerry Stuckle wrote:

> On 6/5/2014 11:36 PM, Chuck Anderson wrote:

>> I feel I'm about to step into a giant pile of doo, but .... Some years
>> back I used a Windows program from Analogx called listmaster pro to
>> verify email addresses manually

> And how did it know?

> For instance - I have three domains.  You can send and email to any
> address at any of the three.  But unless it's a valid address, the email
> ends up in /dev/null.

Which brings us back round to:

The only way to guarantee that an email address is actually going to the 
entity that entered it on your form is to send a verification code to the 
email address.

And even then, I suspect that there are some smart spamming systems out 
there that have email addresses and use eg curl to process the email 
verification links (which is why I use entity and not person above).

-- 
Denis McMahon, denismfmcmahon@gmail.com

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#13804

On 06/06/14 15:37, Denis McMahon wrote:
> On Fri, 06 Jun 2014 09:41:05 -0400, Jerry Stuckle wrote:
>
>> On 6/5/2014 11:36 PM, Chuck Anderson wrote:
>
>>> I feel I'm about to step into a giant pile of doo, but .... Some years
>>> back I used a Windows program from Analogx called listmaster pro to
>>> verify email addresses manually
>
>> And how did it know?
>
>> For instance - I have three domains.  You can send and email to any
>> address at any of the three.  But unless it's a valid address, the email
>> ends up in /dev/null.
>
> Which brings us back round to:
>
> The only way to guarantee that an email address is actually going to the
> entity that entered it on your form is to send a verification code to the
> email address.
>
> And even then, I suspect that there are some smart spamming systems out
> there that have email addresses and use eg curl to process the email
> verification links (which is why I use entity and not person above).
>
I juts love all this 'guarantee' when getting spam don from 99 to 1 
would be a satisfactory result.

I don't care if I get false negatives ads long as the 99 true negatives 
get rejected.


-- 
Ineptocracy

(in-ep-toc’-ra-cy) – a system of government where the least capable to 
lead are elected by the least capable of producing, and where the 
members of society least likely to sustain themselves or succeed, are 
rewarded with goods and services paid for by the confiscated wealth of a 
diminishing number of producers.

[toc] | [prev] | [next] | [standalone]

#13805

["Followup-To:" header set to comp.os.linux.misc.]

On 2014-06-06, The Natural Philosopher <tnp@invalid.invalid> wrote:
>
> I juts love all this 'guarantee' when getting spam don from 99 to 1 
> would be a satisfactory result.

You will almost certainly not get down to 99:1 with any method that
doesn't involve sending mail out with a token, and waiting for the user
to ack the token.  My WAG is you might get down to 50:50.  Other folks
might have different, better-informed guesses.

--keith



-- 
kkeller-usenet@wombat.san-francisco.ca.us
(try just my userid to email me)
AOLSFAQ=http://www.therockgarden.ca/aolsfaq.txt
see X- headers for PGP signature information

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#13785

On 6/4/2014 8:48 PM, The Natural Philosopher wrote:
> I have web contact pages which are used by anyone to send enquiries.
>
> I want to make sure that anyone using them has a valid reply address set
> in a web form BEFORE I forward the message on to the site administrators.
>
>
> Mailer is exim, and that's currently but not necessarily invoked by the
> php mail() function.
>
>
> what I want is a function like
>
> is_valid_mail("user12345@gmail.com")
>
> that will return true or false if gmail accepts the user as known (yes
> the spam is always @gmail.com) WITHOUT having to write a dns mx lookup,
> then connect to socket 25 and etc etc etc..
>
> exim -bt tells me if the domain is valid, but not the user.
>
> I am not particular how its achieved - anything can be merged into the
> existing code.
>
> anyone done this?
>
>

The only way you can do this is to send an email to the address they 
specify and require a response.  While you can determine if a domain 
name is invalid, there is no way to determine whether an email within a 
domain is valid without requiring a response from that email address.

I know you won't see this, but others who might have a similar question 
will.


-- 
==================
Remove the "x" from my email address
Jerry Stuckle
jstucklex@attglobal.net
==================

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#13791

"The Natural Philosopher" <tnp@invalid.invalid> schreef in bericht 
news:lmoeok$5v6$1@news.albasani.net...
> what I want is a function like
>
> is_valid_mail("user12345@gmail.com")
>
> that will return true or false if gmail accepts the user as known (yes the 
> spam is always @gmail.com) WITHOUT having to write a dns mx lookup, then 
> connect to socket 25 and etc etc etc..
>
> exim -bt tells me if the domain is valid, but not the user.
>
> I am not particular how its achieved - anything can be merged into the 
> existing code.

As an idea to work on:

is_valid_mail() checks your database for known users.
If unknown, display a 'verify first' page.
Present a unique code which the user has to mail back to you.
Still not 100% save, but if a user can send using a certain address, there's 
reason to believe he can receive as well. Add the user to your database.

Not enough?
Make it a three way handshake.
The user mails you his code, your autoresponder sends (after verifying the 
code, obviously) another unique code.
Your form checks { is_valid_mail() or presents_valid_code() }
You now have proof email traffic is possible in both directions.

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