530 Recipient refused

[gretchendv]

I have an odd situation. My user (jen@example.com) is able to email a particular customer, but when he replies he receives the following error message and the email is not delivered to my user:
A message that you sent could not be delivered to one or more of
its recipients. The following addresses failed:

<jen@example.com>

SMTP error from remote server after RCPT command:
host example.com[208.89.163.xxx]:
530 Recipient refused.

I went into the smtp log and found the following entry:
Tue, 05 Jan 2010 09:48:22 -> 74.208.4.xxx -> Failed: Action=[Received Recipient], Details=[cru@example.com: IP listed in SPAM Trap.]
Tue, 05 Jan 2010 09:48:22 -> 74.208.4.xxx -> Failed: Action=[Received Recipient], Details=[jen@example.com: IP listed in SPAM Trap.]

I went into my spam trap text file and looked for the ip addresses associated with the sender and both recipients and none of them are listed in the spam trap. In addition both of the recipients are white listed. I think there's something about the sender that is causing this problem, but I simply don't know what that is! The error messages seem to point to the recipients as having a problem, but they are able to receive email from everyone else. Have you seen this problem before? My plan is to white list the sender, hopefully that will help?

[Code Crafters]

The error is indicating that the sender IP has triggered the SPAM trap. The SPAM trap works by you adding an email address as a trigger that isn't really hosted on your mail server but is instead hidden in the HTML of your website to catch SPAM bots that trail your site for email addresses to SPAM. The SPAM trap file is only updated periodically from memory so the IP may not have been in when you checked but the IP listed in the logs lines you sent should be in there. You can indeed SPAM white list the SMTP Sender address or Sender IP for this user providing their IP doesn't change regularly as with dynamic IPs. You could also choose to set the SPAM flag instead of rejecting (deleting) the email when it triggers the SPAM filters then allow content filtering to flag SPAM in the subject using the SPAM identifier preset and move it to a junk folder or send a copy to a backup email address and delete the original so the message can be retrieved. Ideally you should save all your SPAM mails in a junk folder to train the Bayesian with too. We recommend the following SPAM setup:

Basic Filtering:
1) Make sure you’re running version 2.70.
2) Run the SPAM wizard from the dialog admin interface for medium level protection.
3) Set up any black / white listing that you need. The relaying exemption option will allow any authenticated users to bypass SPAM filtering.

Advanced Filtering:
4) If you want to also do Bayesian filtering, this take a bit of setting up but is by far the most effective SPAM filter available today.
a) Set up Bayesian filtering to use only the Auto-Learn from Users training method. Add participating users and appropriate SPAM / non-SPAM folders to the Bayesian settings.
b) Get Participating users to sort their mail into SPAM / non-SPAM folders where Bayesian will automatically learn from them periodically.
c) You need to disable rejecting (deleting) the email on all SPAM filters so that the SPAM flag is set and the mail is allowed to pass through.
d) Set up Content Filtering with the Preset Content Filter Rule (Add Preset button) “SPAM Identifier”. This rule will mark SPAM detected mails with <SPAM> in the subject so that they can be more easily identified and moved to the SPAM folder. Bayesian is a learning system so once it is well trained (minimum of 1000 SPAM and 1000 non-SPAM mails) you can set this content filter rule to also place mails in the SPAM account directory but don’t do this until you are happy it is training accurately and you must then check your SPAM folder for false positives (mails wrongly marked as SPAM that aren’t really SPAM) and move them appropriately.