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Re: FORMS, validating mail was sent

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Hi,

I've top-posted for two reasons:  1, It's a lot of good info that bears 
repitition at lease once, and 2, it's a long post so rather than have 
people CTRL-Ending or worse scrolling to the bottom for the response, 
this makes it more immediate.

That's a great response and verifiable, which many are not. Some of it I 
already knew, a lot of it was great clarification, and I learned a lot.

KUDOS!

Twayne`




On 2013-06-23 7:13 AM, Thomas 'PointedEars' Lahn wrote:
> Gordon Burditt wrote:
>
>> + Your mail was dropped on the floor for having an invalid
>> From: address.  Valid From: addresses likely include ONLY
>> those with the host name of the server you are sending
>> from and a known valid user on that system.  Typically
>> only a few users like root can send mail with 'fake'
>> (off-system) From: addresses.  Hint: Do NOT put a
>> user-supplied email address in the From: header.
>
> Utter nonsense.  By that logic, Web-mail like GMail could not possibly work,
> and it would not be possible to have large e-mail providers in the first
> place (because the host name of their servers very likely differs from the
> domain of the From header field address).
>
> Valid From addresses include all that meet the Address Specification in
> RFC 5322, instead.  This is a purely *syntactical* determination.  It is the
> fact that even addresses for which there are no mailboxes at the sending
> server can be used in the From header field value, and that afterwards
> checking of addresses is unreliable, that allows spammers to thrive.
>
> One must differentiate between the address used as parameter for the MAIL
> FROM (SMTP) command (the “Envelope-From”), and the “From” Internet message
> header field.  The latter can be anything; the former can, in theory, be
> anything unless the *sending* MTA enables counter-measures.  It is not
> possible to change the Envelope-From with simple PHP commands like mail() as
> that is determined by the MTA (like sendmail) used by the PHP executable.
>
> The only good part of this answer is the notion that you invite spammers if
> you let the end user specify the From header field address without
> authentification; so you should not do that, indeed.  The /modus operandi/
> of spammers and phishers is to harvest or buy e-mail addresses from various
> sources and use them also in the “From” header field value to make the
> message look to the recipient like a legitimate e-mail (at first).  This
> kind of network abuse is also supported by “open relays” – MTAs that would
> accept and transfer mail for any MAIL FROM to any RCPT TO.
>
>> + The intended recipient has a slow DNS server.  If you
>> send emails to 100 recipients at a time, it is likely
>> that at least a couple of them have slow DNS servers or
>> overloaded mail servers.  The mail will stay in the queue
>> until the message has been delivered to all recipients,
>> and that can take days, even if 98 of them were delivered
>> in the first minute.
>
> Utter nonsense.  DNS is only used to resolve the target host of the message,
> specifically to retrieve the host name from the “MX” or “A”/“AAAA” record of
> the target domain, and subsequently to resolve the IP address for that host
> name from its “A” or “AAAA” record (this double-handshake is intended as a
> safety feature of DNS/SMTP: there must be a host *name* for an MX).  There
> are no DNS servers anywhere that have a respond time of minutes that would
> suggest the remote possibility of a delay of days because of DNS issues
> (after all, a backup DNS server is strongly recommended, and there are non-
> authoritative answers).
>
> When in rare cases e-mails arrive days later, it is usually due greylisting
> and a long sender or receiver message queue that needs to be worked through;
> not DNS issues at the receiver's (BTST).  Also, the mail queue contains a
> *copy* of the message for each recipient (not least because in the worst
> case each copy must be sent to a different host).  Only those copies that
> have not been sent are still in the queue, not the single original message
> (“the mail”) itself.
>
> “Overloaded mail servers” also are unlikely to be a reason why a message
> stays in the sending queue, because receiving MTAs *also* have an *incoming*
> message queue which is worked through to put the message into the
> corresponding receivers' mailboxes.  Overloading is more likely the reason
> why the message does not arrive at the recipient's mailbox sooner, but that
> has nothing to do with the message transfer between the MTAs, and nothing
> with the sending MTA's outgoing message queue.
>
>>> But you cant execute that without root privileges. Which means having
>>> that level of access to the machine and writing an su 'ed wrapper in C
>>> and calling that instead.
>>
>> Sometimes you can get a queue count without root privileges.  The
>> program that comes with the MTA for this is likely already setuid-root,
>> and you may be able to configure allowing ordinary users to get a
>> queue count.
>
> man sudo
>
>
> PointedEars
>

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FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-20 13:40 -0400
  Re: FORMS, validating mail was sent Jerry Stuckle <jstucklex@attglobal.net> - 2013-06-20 13:53 -0400
  Re: FORMS, validating mail was sent "J.O. Aho" <user@example.net> - 2013-06-20 20:18 +0200
  Re: FORMS, validating mail was sent The Natural Philosopher <tnp@invalid.invalid> - 2013-06-20 19:24 +0100
    Re: FORMS, validating mail was sent Jerry Stuckle <jstucklex@attglobal.net> - 2013-06-20 14:40 -0400
    Re: FORMS, validating mail was sent gordonb.vb4vo@burditt.org (Gordon Burditt) - 2013-06-20 14:44 -0500
      Re: FORMS, validating mail was sent The Natural Philosopher <tnp@invalid.invalid> - 2013-06-20 22:03 +0100
      Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-21 14:06 -0400
      Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-22 11:42 -0400
      Re: FORMS, validating mail was sent Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-23 13:13 +0200
        Re: FORMS, validating mail was sent The Natural Philosopher <tnp@invalid.invalid> - 2013-06-23 12:22 +0100
          Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-23 13:07 -0400
        Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-23 13:00 -0400
          Re: FORMS, validating mail was sent "J.O. Aho" <user@example.net> - 2013-06-23 20:22 +0200
            Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-23 14:53 -0400
        Re: FORMS, validating mail was sent gordonb.4qaft@burditt.org (Gordon Burditt) - 2013-06-24 14:43 -0500
          Re: FORMS, validating mail was sent "Peter H. Coffin" <hellsop@ninehells.com> - 2013-06-24 15:09 -0500
          Re: FORMS, validating mail was sent Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-25 15:19 +0200
            Re: FORMS, validating mail was sent Jerry Stuckle <jstucklex@attglobal.net> - 2013-06-25 10:11 -0400
              Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-25 11:43 -0400
            Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-25 11:32 -0400
            Re: FORMS, validating mail was sent gordonb.htsnc@burditt.org (Gordon Burditt) - 2013-06-27 10:57 -0500
              Re: FORMS, validating mail was sent Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2013-06-27 21:13 +0200
            Re: FORMS, validating mail was sent Arno Welzel <usenet@arnowelzel.de> - 2013-06-28 11:43 +0200
  Re: FORMS, validating mail was sent gordonb.k0cb7@burditt.org (Gordon Burditt) - 2013-06-20 15:46 -0500
    Re: FORMS, validating mail was sent Jerry Stuckle <jstucklex@attglobal.net> - 2013-06-20 17:03 -0400
      Re: FORMS, validating mail was sent gordonb.udxst@burditt.org (Gordon Burditt) - 2013-06-21 19:26 -0500
        Re: FORMS, validating mail was sent Jerry Stuckle <jstucklex@attglobal.net> - 2013-06-21 20:36 -0400
      Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-22 12:04 -0400
    Re: FORMS, validating mail was sent Christoph Michael Becker <cmbecker69@arcor.de> - 2013-06-20 23:39 +0200
      Re: FORMS, validating mail was sent Tim Streater <timstreater@greenbee.net> - 2013-06-21 10:11 +0100
        Re: FORMS, validating mail was sent The Natural Philosopher <tnp@invalid.invalid> - 2013-06-21 11:25 +0100
          Re: FORMS, validating mail was sent Tim Streater <timstreater@greenbee.net> - 2013-06-21 12:27 +0100
            Re: FORMS, validating mail was sent The Natural Philosopher <tnp@invalid.invalid> - 2013-06-21 17:59 +0100
              Re: FORMS, validating mail was sent Tim Streater <timstreater@greenbee.net> - 2013-06-21 18:25 +0100
                Re: FORMS, validating mail was sent The Natural Philosopher <tnp@invalid.invalid> - 2013-06-21 23:43 +0100
                Re: FORMS, validating mail was sent Tim Streater <timstreater@greenbee.net> - 2013-06-22 13:45 +0100
          Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-22 12:20 -0400
    Re: FORMS, validating mail was sent "Peter H. Coffin" <hellsop@ninehells.com> - 2013-06-20 17:27 -0500
      Re: FORMS, validating mail was sent The Natural Philosopher <tnp@invalid.invalid> - 2013-06-21 07:57 +0100
    Re: FORMS, validating mail was sent Twayne <nobody@spamcop.net> - 2013-06-22 12:02 -0400
  Re: FORMS, validating mail was sent GravyCode <matty023@gmail.com> - 2013-06-21 11:30 -0700

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