Rate Limit @ Hostgator & QueueIfDestinationError
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=6842
Printed Date: 05 February 2025 at 7:45am
Topic: Rate Limit @ Hostgator & QueueIfDestinationError
Posted By: yapadu
Subject: Rate Limit @ Hostgator & QueueIfDestinationError
Date Posted: 04 June 2010 at 9:44pm
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Hi have been noticing over the past few days problems delivering email to some of hostgator's servers. They are using some type of rate limit (I think they just started doing this recently), when you go over the limit you get this: 451-The server has reached its limit for processing requests from your host. 451 Please try again later. Messages are automatically bounced back to sender when spamfilter gets this. We have the following enabled: QueueIfDestinationError400=1 It seems like with a 4xx error spamfilter should be holding the messages and trying again later, not rejecting them outright. Is this a bug, or am I missing something? ------------- -------------------------------------------------------------- I am a user of SF, not an employee. Use any advice offered at your own risk. |
Replies:
Posted By: LogSat
Date Posted: 05 June 2010 at 2:14pm
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yapadu, Could you please zip us a section of SpamFilter's activity logfile that contains the entries to one such email, so we can take a look? The setting you set to "1" should indeed cause the email to be queued, without a bounce back to be created. ------------- 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: yapadu
Date Posted: 29 June 2010 at 9:59am
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Here is a snippet of my .ini file: ;Determines if SpamFilter should hold in the queue emails that were rejected by the destination SMTP server with an error in the 4xy range QueueIfDestinationError400=1 ;Determines if SpamFilter should hold in the queue emails that were rejected by the destination SMTP server with an error in the 5xy range QueueIfDestinationError500=0 Here is a transaction from my log, trying to push an email to a server hosted with hostgator (who like to rate limit us!) 06/29/10 13:33:07:074 -- (1216) Detected TCP Connection: (SSL) 172.16.15.209 06/29/10 13:33:07:074 -- (1216) Connection from: 172.16.15.209 06/29/10 13:33:08:840 -- (1216) User authenticated with AUTH LOGIN: sender@undp.org 06/29/10 13:33:09:059 -- (1216) Received MAIL FROM: <sender@undp.org> 06/29/10 13:33:09:246 -- (1216) Received RCPT TO: dcam@example.com 06/29/10 13:33:09:246 -- (1216) Bypassed all rules for: dcam@example.com from sender@undp.org ( User authenticated with AUTH LOGIN) 06/29/10 13:33:11:090 -- (1216) Start virus scan 06/29/10 13:33:11:137 -- (1216) Starting queueing procedures 06/29/10 13:33:11:137 -- (1216) EMail from sender@undp.org to dcam@example.com was queued. Size: 21 KB, 21504 bytes 06/29/10 13:33:11:137 -- (4392) Sending email from sender@undp.org to dcam@example.com -- 06/29/10 13:33:11:387 -- (4392) EMail from: sender@undp.org to: dcam@example.com -- was returned to sender - server error - example.com:25 said: The server has reached its limit for processing requests from your host. -- Please try again later. -- 06/29/10 13:33:11:559 -- (4392) Error-email from sender@undp.org to dcam@example.com -- was forwarded to mail.undp.org:25 06/29/10 13:33:11:559 -- (4392) server error - example.com:25 said: The server has reached its limit for processing requests from your host. -- Please try again later. -- At that point the message is bounced. The bounce says: The specific error is: server error - example.com:25 said: The server has reached its limit for processing requests from your host. Please try again later. I just tried a telnet session to the remote server to execute a delivery attempt by hand to see what the message is, but they are not blocking us right this moment. file:///C:%5CUsers%5Crgunther%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml - ------------- -------------------------------------------------------------- I am a user of SF, not an employee. Use any advice offered at your own risk. |
Posted By: yapadu
Date Posted: 29 June 2010 at 10:02am
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This problem went away for a while, because we were able to get hostgator to whitelist our sending address. However, they removed the whitelist and the problem is back again.
------------- -------------------------------------------------------------- I am a user of SF, not an employee. Use any advice offered at your own risk. |
Posted By: LogSat
Date Posted: 30 June 2010 at 1:25am
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Ok, this was a tricky one, and I should have caught it from your initial post:
Note how the initial reply line (the initial reply is the one that matters) has the digits 451 followed by a dash and then a description. From RFC 2821, which is the standard to which all SMTP server *must* abide to, the following section states: 2.4 General Syntax Principles and Transaction Model SMTP commands and replies have a rigid syntax. All commands begin with a command verb. All Replies begin with a three digit numeric code. In some commands and replies, arguments MUST follow the verb or reply code. Some commands do not accept arguments (after the verb), and some reply codes are followed, sometimes optionally, by free form text. In both cases, where text appears, it is separated from the verb or reply code by a space character. This means that hostgator's server is in violation of RFC, as the response should have been: 451 The server has reached its limit for processing requests from your host. With a [space] instead of the [-] after the 451. The second line in orange that they output: 451 Please try again later. does have, correctly, a space, but that is too late, as it is the line above that is considered the reply, and it does not follow RFC. At that point, the reply is invalid as it does not contain a valid numeric code, and thus SpamFilter does not recognize the 451 as such. ------------- Roberto Franceschetti http://www.logsat.com" rel="nofollow - LogSat Software http://www.logsat.com/sfi-spam-filter.asp" rel="nofollow - Spam Filter ISP |
yapadu wrote:Posted By: yapadu
Date Posted: 30 June 2010 at 1:46am
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Bad bad hostgator! I noticed another issue with them recently. One of their servers connected to one of ours and got a 421 from us for greylisting. They bounced the email right away, did not retry or try a server with lower priority either. These large ISP/hosting companies are tough to deal with! ------------- -------------------------------------------------------------- I am a user of SF, not an employee. Use any advice offered at your own risk. |