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Delivery to wrong server

Printed From: LogSat Software
Category: Spam Filter ISP
Forum Name: Spam Filter ISP Support
Forum Description: General support for Spam Filter ISP
URL: https://www.logsat.com/spamfilter/forums/forum_posts.asp?TID=5311
Printed Date: 26 December 2024 at 4:08pm


Topic: Delivery to wrong server
Posted By: agavv
Subject: Delivery to wrong server
Date Posted: 22 August 2005 at 11:01am

In my logs I found something strange:

(1152) Mail from: mailto:Remko@qqqqq.com - Remko@qqqqq.com
(1152) - MAPS search done... 
(1152) RCPT TO: mailto:info@aaaaa.nl - info@aaaaa.nl accepted
(1152) Mail from: mailto:Remko@qqqqq.com - Remko@qqqqq.com
(1152) RCPT TO: mailto:info@bbbbb.nl - info@bbbbb.nl accepted
(1152) Mail from: mailto:Remko@qqqqq.com - Remko@qqqqq.com
(1152) RCPT TO: info mailto:info@ccccc.nl - @ccccc.nl accepted
(1152) Warning - Message exceeds MaxMsgSizeForKeywordScan, skipping statistical scan
(1152) EMail from mailto:Remko@qqqqq.com - Remko@qqqqq.com to mailto:info@aaaaa.nl - info@aaaaa.nl , mailto:info@bbbbb.nl - info@bbbbb.nl , info mailto:info@ccccc.nl - @ccccc.nl passes Bayesian filter - 0% spam  (0ms)
(1152) EMail from mailto:Remko@qqqqq.com - Remko@qqqqq.com to mailto:info@aaaaa.nl - info@aaaaa.nl , mailto:info@bbbbb.nl - info@bbbbb.nl , info mailto:info@ccccc.nl - @ccccc.nl was queued. Size: 1595 KB, 1633280 bytes
(848) Sending email from mailto:Remko@qqqqq.com - Remko@qqqqq.com to mailto:info@aaaaa.nl - info@aaaaa.nl , mailto:info@bbbbb.nl - info@bbbbb.nl , info mailto:info@ccccc.nl - @ccccc.nl  
(848) EMail from mailto:Remko@qqqqq-nl.com - Remko@qqqqq-nl.com to mailto:info@aaaaa.nl - info@aaaaa.nl , mailto:info@bbbbb.nl - info@bbbbb.nl , info mailto:info@ccccc.nl - @ccccc.nl   was forwarded to xx.xx.13.68:25
(848) Some recipients do not exist, sending NDR bounce to sender
(848) EMail from: mailto:Remko@qqqqq.com - Remko@qqqqq.com to: mailto:info@bbbbb.nl - info@bbbbb.nl , mailto:info@ccccc.nl - info@ccccc.nl was returned to sender - The following recipients are unknown: mailto:info@bbbbb.nl - info@bbbbb.nl , info mailto:info@ccccc.nl - @ccccc.nl

The first domain uses its own mailserver: aaaaa.nl:xx.xx.13.68:25 and the domains bbbbb.nl and ccccc.nl use our (default) mailserver. These last two emailaddresses are on our mailserver but SF tried to post to the server of aaaaa.nl. We use v.2.6.3.473.

I don't know if it is a new bug, but we have not seen this happening the last three years and we are happy to use SF.

Ab

 

 


Replies:
Posted By: LogSat
Date Posted: 22 August 2005 at 1:31pm
Ab,

Can you please check the domains listed in your LocalDomains, and see if you have any duplicate entries? SpamFilter tries to double-check the file to eliminate duplicates if possible, but we found a bug in the latest build where this "housekeeping" procedure will sometimes not detect duplicate domains.


-------------
Roberto Franceschetti

http://www.logsat.com" rel="nofollow - LogSat Software

http://www.logsat.com/sfi-spam-filter.asp" rel="nofollow - Spam Filter ISP

Posted By: agavv
Date Posted: 23 August 2005 at 4:57pm

Roberto,

There are no duplicates in the list and these domains are there for a long time without any changes.

I found a change after updating to this version in rejecting non-existing emailaddresses. In the past the email was rejected if one address in the cc-list was not valid and now only the bad addresses are rejected and the rest is going thru. Has this anything to do with it?

Ab

Posted By: LogSat
Date Posted: 24 August 2005 at 9:53pm
Ab,

We found what happened.

The email was send to multiple recipients:

info@aaaaa.nl
info@bbbbb.nl
info@ccccc.nl

SpamFilter delievers the email "as is" to the destination SMTP server. In this case, the email has one recipient to the aaaaaa.nl domain, and the other two to bbbbbb.nl and ccccc.nl. As SpamFilter cannot "split" the email and deliver a copy to each of the servers responsible for each of the domains, all it can do it to take the first destination SMTP server, (the one for aaaaaa.nl), and forward the email to it.

Unfortunately there is currently no workaround for this behavior. We may alter the way email is forwarded in the future to address this issue, but we don't have any estimates on when this will be available.



-------------
Roberto Franceschetti

http://www.logsat.com" rel="nofollow - LogSat Software

http://www.logsat.com/sfi-spam-filter.asp" rel="nofollow - Spam Filter ISP

Posted By: pcmatt
Date Posted: 27 August 2005 at 9:47am

I'm just curious. 

What's the SMTP RFC spec on relaying in this case? 

If SpamFilter is operating per SMTP specifications then the cc's should have been delivered and the sending server is the problem.

If SpamFilter is broken, then I would hope this gets fixed before new features like the DNA fingerprinting I read about. Not delivering email as addressed is a major flaw.

I don't know the spec on this so I can't say either way if SF is broken or not.

 



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-Matt R

Posted By: LogSat
Date Posted: 27 August 2005 at 10:26am
The RFC states that if an email cannot be delivered then the sender MUST be notified of the non delivery.

In the above example, one address is accepted by the destination SMTP server, the other two are rejected. SpamFilter will thus deliver the email to the accepted recipient, and does indeed send a non-delivery notice to the sender informing them that their email did not get to the other two recipients (and lists the addresses that were underliverable).

The destination SMTP server is behaving per RFC by rejecting the recipients it does not support. SpamFilter is also behaving per RFC by informing the sender of the delivery problems with the two recipients.

The RFC that we apply in this case is RFC 2821 (http://www.rfc-editor.org/rfc/rfc2821.txt). The section you'll want to refer to is 3.7 on page 24:

   If an SMTP server has accepted the task of relaying the mail and
   later finds that the destination is incorrect or that the mail cannot
   be delivered for some other reason, then it MUST construct an
   "undeliverable mail" notification message and send it to the
   originator of the undeliverable mail (as indicated by the reverse-
   path).  Formats specified for non-delivery reports by other standards
   (see, for example, [24, 25]) SHOULD be used if possible.



-------------
Roberto Franceschetti

http://www.logsat.com" rel="nofollow - LogSat Software

http://www.logsat.com/sfi-spam-filter.asp" rel="nofollow - Spam Filter ISP

Posted By: pcmatt
Date Posted: 27 August 2005 at 10:39am

I must have misunderstood the original post.  It sounded to me that SpamFilter did not route the different recipients properly causing NDR's.  It sounded like there should not have been NDR's because the default Destination Server was not used per your original design. 

I thought SpamFilter was to route recipients based on the Local Domains whitelist table first and then route everything else to the default Destination Server.  The last two emails should have been forwarded to the default Destination Server as is specified by your docs not the whitelisted domain. 

Is my understanding incorrect or did you understand the user's post to say different?



-------------
-Matt R

Posted By: LogSat
Date Posted: 27 August 2005 at 4:24pm
Matt,

The original user's post is accurate, he does describe a behavior in SpamFilter which could be indeed improved. He states that:

1. An email arrives with multiple recipients for multiple domains he owns
2. Some of the domains for the above recipients have different destination SMTP servers
3. The different destination SMTP servers will reject recipients for domains they do not handle

If the above conditions are true, some recipients will received NDRs. My second reply applies:

As SpamFilter cannot "split" the email and deliver a copy to each of the servers responsible for each of the domains, all it can do it to take the first destination SMTP server, (the one for aaaaaa.nl), and forward the email to it.
Unfortunately there is currently no workaround for this behavior. We may alter the way email is forwarded in the future to address this issue, but we don't have any estimates on when this will be available.



-------------
Roberto Franceschetti

http://www.logsat.com" rel="nofollow - LogSat Software

http://www.logsat.com/sfi-spam-filter.asp" rel="nofollow - Spam Filter ISP

Posted By: pcmatt
Date Posted: 27 August 2005 at 9:01pm

Ok, I think I understand correctly now:

SpamFilter currently requires that recipient servers for approved domains relay email for domains homed on a server that differs from the default recipient domain?

The solution, then, for agavv is to ensure that his/her servers will relay email from his/her SpamFilter server to other servers. That way the approved domain server can complete the job and relay the copies of the email to the recipients that are not local. 

So, the future improvement would make SpamFilter operate in a more standard fashion when handling SMTP Client transmissions for approved domains.  Once SpamFilter has accepted an email from a sending client, it should then assumes a client role in delivering to recipients in approved domains.  That means SpamFilter will send a copy of the email to each accepted recipient per the rules and configurations of SpamFilter and in accordance with the this paragraph on page 23 of Section 3.7 SMTP RFC:

A relay SMTP server is usually the target of a DNS MX record that
designates it, rather than the final delivery system.  The relay
server may accept or reject the task of relaying the mail in the same  way it accepts or rejects mail for a local user.  If it accepts the task, it then becomes an SMTP client, establishes a transmission channel to the next SMTP server specified in the DNS (according to the rules in section 5), and sends it the mail.



-------------
-Matt R

Posted By: agavv
Date Posted: 28 August 2005 at 11:05am

Roberto,

This is very bad news! The three customers I mentioned are competitors. Two use POP3-boxes on our server and one runs it's own mailserver. They received a very important message from a distributor and the one with his own mailserver, saw his server rejecting the e-mails for the two competitors on our mailserver.... I have to explain this!!

All three have ONE MX-record pointing to SF. Our mailserver can only forward to domains with a valid MX-record and we let SF forward the mail to a A-record.

Maybe you can make a workaround by sending the email with different destinations to the default server. Our mailserver forwards the email for delivering to SF (again) and SF sends it to the correct destination.

We have a mix of customers with POP3-boxes on our mailserver and customers who have their own mailserver. We cannot ask the rest of the world to stop with cc's and we can also not ask our customers to install a POP3-connector on their Exchange servers.

I hope you come with a solution for this!

Ab

 

Posted By: pcmatt
Date Posted: 28 August 2005 at 10:44pm

agavv

I tested this on our many domains. Using latest build it appears that your problems are solved if you merely define the smtp server for each inbound approved domain.  SpamFilter send copies to multiple local domains in my tests per RFC specs above.  It looks like the only issue is when you are relying on the default server.

So, in your case if you specify the inbound domains in the Local Domains whitelist for example:

aaaaa.nl:mail.aaaaa.nl:25
bbbbb.nl:mail.bbbbb.nl:25
ccccc.nl:mail.ccccc.nl:25

(where mail. is the mail host for the given domain) you will not have problems.  So it appears you are only having problems because either you have not included all local domains in your Local Domains whitelist or have not specified the mail server:port for each Local Domain entry. 



-------------
-Matt R

Posted By: Guests
Date Posted: 29 August 2005 at 8:13pm

There is a very simple solution for this problem.

You can ask your default destination smtp server to relay for domains you host but are located on remote boxes. just create a route.

since your default destination smtp server is already behind SF you already control which domains you accept email for.

hope this helps

Sam

 


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