Anonymous_User Absent Member.
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DSN

Do you allow or disable Delivery Status Notifications?



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dzanre1 Absent Member.
Absent Member.

Re: DSN

Craig wrote:

> Do you allow or disable Delivery Status Notifications?


Yeah.

--
Danita
Novell Knowledge Partner
Time to upgrade to GW8!
http://www.caledonia.net/gw8upg.html
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Anonymous_User Absent Member.
Absent Member.

Re: DSN

You mean, you alow DSNs and NDRs?


"DZanre" <dzanre@no-mx.forums.novell.com> wrote in message
news:gemini.kjusjn000343g00hh.dzanre@no-mx.forums.novell.com...
> Craig wrote:
>
>> Do you allow or disable Delivery Status Notifications?

>
> Yeah.
>
> --
> Danita
> Novell Knowledge Partner
> Time to upgrade to GW8!
> http://www.caledonia.net/gw8upg.html



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dzanre1 Absent Member.
Absent Member.

Re: DSN

Craig wrote:

> You mean, you alow DSNs and NDRs?


The internet would be almost broken if you didn't allow for non-delivery
reports. Wouldn't you be frustrated if you thought you sent me a message,
but because you mistyped my name the message failed?

But it depends on what you mean by NDR of course. A standard NDR that talks
mail-server to mail-server is vital to proper email management. If you mean
though where a server just accepts mail and then reports back later that
it's been undelivered, no. Don't do that. Of course there are cases on any
email system where that can occur accidentally (like a user gets deleted,
but somehow the receiving mail server isn't aware of that. But no, we do
not allow undeliverable reports other than those that are generated by the
server at time of reception.

GroupWise will allow for DSN that tells that a message was actually posted
to a mailbox, but that's a "delivery" report, after the mail has been
properly accepted for a real user. A lot of GW sites will allow for that
but they don't turn on any other form of confirmation.

So, yeah, we allow for BOTH DSN and NDR depending on the definitions 🙂

--
Danita
Novell Knowledge Partner
Time to upgrade to GW8!
http://www.caledonia.net/gw8upg.html
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Anonymous_User Absent Member.
Absent Member.

Re: DSN

But what about DHAs? They can bombard your mail server and pretend to be
from abc.com, etc.

Then abc.com gets the NDR for a@abc.com, b@abc.com , c@abc.com all from
caledonia . net?


"DZanre" <dzanre@no-mx.forums.novell.com> wrote in message
news:gemini.kjvc2l0000lul006t.dzanre@no-mx.forums.novell.com...
> Craig wrote:
>
>> You mean, you alow DSNs and NDRs?

>
> The internet would be almost broken if you didn't allow for non-delivery
> reports. Wouldn't you be frustrated if you thought you sent me a message,
> but because you mistyped my name the message failed?
>
> But it depends on what you mean by NDR of course. A standard NDR that
> talks
> mail-server to mail-server is vital to proper email management. If you
> mean
> though where a server just accepts mail and then reports back later that
> it's been undelivered, no. Don't do that. Of course there are cases on
> any
> email system where that can occur accidentally (like a user gets deleted,
> but somehow the receiving mail server isn't aware of that. But no, we do
> not allow undeliverable reports other than those that are generated by the
> server at time of reception.
>
> GroupWise will allow for DSN that tells that a message was actually posted
> to a mailbox, but that's a "delivery" report, after the mail has been
> properly accepted for a real user. A lot of GW sites will allow for that
> but they don't turn on any other form of confirmation.
>
> So, yeah, we allow for BOTH DSN and NDR depending on the definitions 🙂
>
> --
> Danita
> Novell Knowledge Partner
> Time to upgrade to GW8!
> http://www.caledonia.net/gw8upg.html



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dzanre1 Absent Member.
Absent Member.

Re: DSN

Craig wrote:

> Then abc.com gets the NDR for a@abc.com, b@abc.com , c@abc.com all from
> caledonia . net?


Nope - DHAs are stopped at the very front of the email system, and it just
tells the spoofing server that the user doesn't exist. I never "accept"
mail for people that don't exist. abc.com would never get backscatter in
that way from my servers.

I think you are asking the question incorrectly actually. Do I accept mail
for non-existent users, and then send a NDR out after that? No. Do I tell
a server connecting to me that a user doesn't exist and they should go away?
Absolutely.

Not all NDRs and DSN are "problems" - they are only problems if your mail
servers are misconfigured.

--
Danita
Novell Knowledge Partner
Time to upgrade to GW8!
http://www.caledonia.net/gw8upg.html
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Anonymous_User Absent Member.
Absent Member.

Re: DSN

Sorry to be obtuse...

How does a server distinguish between the following:?

1) email to darnita@caledonia from craig@abc.com

Bounces back to abc.com because danita is misspelled.

2) email <from spam@spoofed.com> to dha@caledonia

NDR returns to spoofed.com even though spoofed never emailed you?





"DZanre" <dzanre@no-mx.forums.novell.com> wrote in message
news:gemini.kjwklp0002mtg006t.dzanre@no-mx.forums.novell.com...
> Craig wrote:
>
>> Then abc.com gets the NDR for a@abc.com, b@abc.com , c@abc.com all from
>> caledonia . net?

>
> Nope - DHAs are stopped at the very front of the email system, and it just
> tells the spoofing server that the user doesn't exist. I never "accept"
> mail for people that don't exist. abc.com would never get backscatter in
> that way from my servers.
>
> I think you are asking the question incorrectly actually. Do I accept
> mail
> for non-existent users, and then send a NDR out after that? No. Do I
> tell
> a server connecting to me that a user doesn't exist and they should go
> away?
> Absolutely.
>
> Not all NDRs and DSN are "problems" - they are only problems if your mail
> servers are misconfigured.
>
> --
> Danita
> Novell Knowledge Partner
> Time to upgrade to GW8!
> http://www.caledonia.net/gw8upg.html



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jcalderwood Absent Member.
Absent Member.

Re: DSN

Craig wrote:
> Sorry to be obtuse...
>


¿¿¿Go on a diet then???
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dzanre1 Absent Member.
Absent Member.

Re: DSN

Craig wrote:

> 1) email to darnita@caledonia from craig@abc.com
>
> Bounces back to abc.com because danita is misspelled.
>
> 2) email <from spam@spoofed.com> to dha@caledonia
>
> NDR returns to spoofed.com even though spoofed never emailed you?


So, here's the deal. As the "receiving" server, it's only my responsibilty
to tell the sending server if a user exists. So, if you work at abc.com,
and send an email to darnita@caledonia, my server will tell your server.
It's then up to your server (the sending server) to let you know that I
don't exist.

So, let's then say a spammer sends mail to dha@caledonia and finds an open
relay server to do it. In theory yes, at that point, spoof.com might
receive what's known as "backscatter" because the sending server is trying
to do it's job, but not very well obviously if it's an open relay and
accepting the junk in the first place!

However, what you find most times in DHA situations is that a PC is sending
the mail directly (not through a relay server) and will never send an
undeliverable anyway. It is not in a spammer's best interest time-wise to
bother 1) creating bogus undeliverables or 2) retry accounts that don't
deliver the first time (hence why greylisting is generally pretty
effective).

In other words, in a DHA it would never be the caledonia server who even
TELLS the sending user (real or fake) that a user doesn't exist. The
caledonia server tells the sending SERVER whether a user exists, and that
server is responsible for alerting the sending user. So in REAL mail, this
works perfectly. abc.com's server dutifully tells only the users that it
sends for that a message didn't go through. If you get caught up in a relay
server sending backscatter, then that relay server is who is going to get
shut down, not the caledonia server. And if it's an infected PC (or just a
PC being used as a spam engine), it will not send undeliverables either,
because it's a waste of the spammer's precious bandwidth.

It would be a horrible thing if mail that was misaddressed, or even simply
no longer deliverable was not acknowledged. How would you like it if you
mailed your mortgage payment to the wrong place, and it just got put in the
trash instead of being returned to you as undeliverable? It is just not
feasible to turn off all types of notification on email either.

--
Danita
Novell Knowledge Partner
Time to upgrade to GW8!
http://www.caledonia.net/gw8upg.html
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Anonymous_User Absent Member.
Absent Member.

Re: DSN

I agree-ish....

To me, if a user or customer believes that email was received and read,
properly addressed and acted upon they're insane. Everybody should treat it
properly......never assume a thing...if it's important send a followup.

RE: Mortgage....I think if I'm late they'll give me a better rate....:)

Seriously, though, the analogy should be if it's important, why didn't you
send it certified mail or FedUp/UPS?

Thanks!


"DZanre" <dzanre@no-mx.forums.novell.com> wrote in message
news:gemini.kjwlje0002rcr006t.dzanre@no-mx.forums.novell.com...
> Craig wrote:
>
>> 1) email to darnita@caledonia from craig@abc.com
>>
>> Bounces back to abc.com because danita is misspelled.
>>
>> 2) email <from spam@spoofed.com> to dha@caledonia
>>
>> NDR returns to spoofed.com even though spoofed never emailed you?

>
> So, here's the deal. As the "receiving" server, it's only my
> responsibilty
> to tell the sending server if a user exists. So, if you work at abc.com,
> and send an email to darnita@caledonia, my server will tell your server.
> It's then up to your server (the sending server) to let you know that I
> don't exist.
>
> So, let's then say a spammer sends mail to dha@caledonia and finds an open
> relay server to do it. In theory yes, at that point, spoof.com might
> receive what's known as "backscatter" because the sending server is trying
> to do it's job, but not very well obviously if it's an open relay and
> accepting the junk in the first place!
>
> However, what you find most times in DHA situations is that a PC is
> sending
> the mail directly (not through a relay server) and will never send an
> undeliverable anyway. It is not in a spammer's best interest time-wise to
> bother 1) creating bogus undeliverables or 2) retry accounts that don't
> deliver the first time (hence why greylisting is generally pretty
> effective).
>
> In other words, in a DHA it would never be the caledonia server who even
> TELLS the sending user (real or fake) that a user doesn't exist. The
> caledonia server tells the sending SERVER whether a user exists, and that
> server is responsible for alerting the sending user. So in REAL mail,
> this
> works perfectly. abc.com's server dutifully tells only the users that it
> sends for that a message didn't go through. If you get caught up in a
> relay
> server sending backscatter, then that relay server is who is going to get
> shut down, not the caledonia server. And if it's an infected PC (or just
> a
> PC being used as a spam engine), it will not send undeliverables either,
> because it's a waste of the spammer's precious bandwidth.
>
> It would be a horrible thing if mail that was misaddressed, or even simply
> no longer deliverable was not acknowledged. How would you like it if you
> mailed your mortgage payment to the wrong place, and it just got put in
> the
> trash instead of being returned to you as undeliverable? It is just not
> feasible to turn off all types of notification on email either.
>
> --
> Danita
> Novell Knowledge Partner
> Time to upgrade to GW8!
> http://www.caledonia.net/gw8upg.html



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dzanre1 Absent Member.
Absent Member.

Re: DSN

Craig wrote:

> Seriously, though, the analogy should be if it's important, why didn't you
> send it certified mail or FedUp/UPS?


Possibly - but there is some expectation by most people that if you send to
the wrong account, you'll know about it. We may get to the point where
sites just throw up their hands and say no delivery status of any kind
(failure or otherwise), but I don't think we're there yet. Where most of
this "backscatter" comes from is old Exchange servers, and old GW servers,
where the mail server just accepts everything, and then figures out at the
mailbox that the user doesn't exist. Few servers do that any longer, so the
only time most backscatter happens is when someone finds an open relay
server. That's an entirely different story of course.

But if REAL mail servers are still practicing the "receive and then reject
later" policies, they are dumb 🙂

--
Danita
Novell Knowledge Partner
Time to upgrade to GW8!
http://www.caledonia.net/gw8upg.html
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Anonymous_User Absent Member.
Absent Member.

Re: DSN

Alright...one more question then...

If you reject a@domain.com and b@domain.com, but then allow c@domain.com did
you inadvertently tell them "you have a winner"?


"DZanre" <dzanre@no-mx.forums.novell.com> wrote in message
news:gemini.kjwnph0002vkg006t.dzanre@no-mx.forums.novell.com...
> Craig wrote:
>
>> Seriously, though, the analogy should be if it's important, why didn't
>> you
>> send it certified mail or FedUp/UPS?

>
> Possibly - but there is some expectation by most people that if you send
> to
> the wrong account, you'll know about it. We may get to the point where
> sites just throw up their hands and say no delivery status of any kind
> (failure or otherwise), but I don't think we're there yet. Where most of
> this "backscatter" comes from is old Exchange servers, and old GW servers,
> where the mail server just accepts everything, and then figures out at the
> mailbox that the user doesn't exist. Few servers do that any longer, so
> the
> only time most backscatter happens is when someone finds an open relay
> server. That's an entirely different story of course.
>
> But if REAL mail servers are still practicing the "receive and then reject
> later" policies, they are dumb 🙂
>
> --
> Danita
> Novell Knowledge Partner
> Time to upgrade to GW8!
> http://www.caledonia.net/gw8upg.html



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dzanre1 Absent Member.
Absent Member.

Re: DSN

Craig wrote:

> If you reject a@domain.com and b@domain.com, but then allow c@domain.com
> did you inadvertently tell them "you have a winner"?


Yep. But life is too short to worry about these things. If you don't have
anti-spam software that is dealing with it AFTER you receive it, then your
users have linched you already anyway 🙂

If your mail server can do selective grey-listing then that's the way to go
too. We only have something like .0001% of greylisted sites ever trying
back again (but we do not greylist everything, just suspicious server names,
no PTR, etc.

--
Danita
Novell Knowledge Partner
Time to upgrade to GW8!
http://www.caledonia.net/gw8upg.html
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