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Re: FORMS, validating mail was sent

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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
-- 
Use any version of Microsoft Frontpage to create your site.
(This won't prevent people from viewing your source, but no one
will want to steal it.)
  -- from <http://www.vortex-webdesign.com/help/hidesource.htm> (404-comp.)

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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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