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timeout and reverse dns now working correctly?

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dcook View Drop Down
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    Posted: 14 October 2003 at 10:28am

Ver 1.0.206

I reciently added the reverse dns lookup feature in spamfilter and it does block a lot of email over and above keywords and maps servers  --- however:

I have had the following problems --

1. Two people were blocked because of "no reverse dns" -- they had a reverse entry- these were false positives.

2. I unfiltered and email address and mail was still blocked to this person because of no reverse DNS.  This sender had a reverse entry and would some times be blocked and other times mail would be delivered.

3. I am seeing a few dns server time outs -- this I believe was the reason in #2 sometimes mail would be blocked.

It was my understanding that whitelisting an email address would override the dns reverse lookup -- that does not seem  to be the case.

I have switched OFF the reverse lookup in spamfilter till I get resolution. 

Dwight Cook

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Desperado Quote  Post ReplyReply Direct Link To This Post Posted: 14 October 2003 at 12:01pm

Dwight,

I, too have found that no RDNS seems to be applied prior to the white list but it hasn't cause me more than one or two issues.  I will shoot this off to logsat support for review.  However, my understanding is that the INTENT is that if DNS does time out, it should not block because the assumption is made that it is a transient condition and better to let it go than block.  Again, if this has changed, I believe it is a bug, not an intentional change.

Dan S.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote LogSat Quote  Post ReplyReply Direct Link To This Post Posted: 15 October 2003 at 12:14am

Dwight,

We're not able to replicate the problems. For this:

<<
1. Two people were blocked because of "no reverse dns" -- they had a reverse entry- these were false positives.
>>

can you please post (or email us at support@logsat.com) with the SpamFilter's activity logfile that show the email being rejected along with IPs and email addresses?


With regards to the whitelists, we're not too clear on which case you are referring. We tested both however, and did not find problems.

The two whitelists you refer in your post are "unfiltered emails" and "whitelisting an email address". They are two different things.

"Unfiltered emails" are local email address who want to receive unfiltered emails. All email addressed to them will bypass all filter rules.

"Whitelisting an email address" we interpreted as "Excluded FROM Emails", which are specific senders that you want to prevent from being filtered by mistake.


As far as the DNS timeouts, in this case the reverse DNS test is ignored, and the other filters are applied.

Following are log examples for all 3 cases:

 

test@logsat.com is in the "Unfiltered Emails":

10/15/03 00:09:46:096 -- (3636) Connection from: 172.27.4.53  -  Originating country : N/A
10/15/03 00:09:46:306 -- (3636) Resolving 172.27.4.53 - Not found
10/15/03 00:09:46:306 -- (3636) Bypassed all rules for: test@logsat.com from rrr@cfl.rr.com
10/15/03 00:09:46:346 -- (3636) EMail from rrr@cfl.rr.com to test@logsat.com was queued. Size: 1 KB
10/15/03 00:09:46:346 -- (3636) Disconnect
10/15/03 00:09:46:356 -- (2284) Sending email from rrr@cfl.rr.com to test@logsat.com
10/15/03 00:09:48:029 -- (2284) EMail from rrr@cfl.rr.com to test@logsat.com  was forwarded to rome:25

The log shows that upon connection the Reverse DNS test fails. But when the remote server sends the recipient, test@logsat.com, it is recognized to be in the "Unfiltered Emails" whitelist, and the email is queued and sent anyways.

 

zzz@cfl.rr.com is in the "Excluded FROM Emails"

10/15/03 00:12:24:351 -- (1284) Connection from: 172.27.4.53  -  Originating country : N/A
10/15/03 00:12:24:551 -- (1284) Resolving 172.27.4.53 - Not found
10/15/03 00:12:24:551 -- (1284) Bypassed all rules for: test2@logsat.com from zzz@cfl.rr.com
10/15/03 00:12:24:602 -- (1284) EMail from zzz@cfl.rr.com to test2@logsat.com was queued. Size: 1 KB
10/15/03 00:12:24:612 -- (1284) Disconnect
10/15/03 00:12:24:612 -- (3520) Sending email from zzz@cfl.rr.com to test2@logsat.com
10/15/03 00:12:25:803 -- (3520) EMail from zzz@cfl.rr.com to test2@logsat.com  was forwarded to rome:25

The log shows that upon connection the Reverse DNS test fails, and then the remote server sends its email address (zzz@cfl.rr.com), it is recognized to be in the "Excluded FROM Emails" whitelist, and the email is queued and sent anyways.

 

If you notice otherwise, can you please post more details using the SpamFilter logs as we did above?

Roberto F.
LogSat Software

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