Posts Tagged ‘rblsmtpd’

How to exclude for a particular IP address in Qmail Mail server install / Fix to Thunderbird mail sent error (Exploitable Server See: error

Tuesday, November 1st, 2011

In the office, some of my colleagues has started receiving error messages, while trying to send mail with Thunderbird and Outlook Express
The exact error they handed to me reads like this:

An error occured while sending mail. The mail server responded: Exploitable Server See: Please check the message recipient

Here is also a screenshot, I’ve been sent via Skype with the error poping up on a Thunderbird installed on Windows host.

Typing the url lead me to to a page saying that the IP address of the mail client which is trying to send mail is blacklisted . This is not strange at all condireng that many of the office computers are running Windows and periodically get infected with Viruses and Spyware which does sent a number of Unsolicated Mail (SPAM).

The record for the IP seems to be an old one, since at the present time the office network was reported to be clear from malicious SMTP traffic.

The error disallowing the mail clients to send from the office continued for already 3 days, so something had to be done.

We asked the ISP to change the blacklisted IP address of xx.xx.xx.xx , to another one but they said it will take some time and they can’t do it in a good timely matter, hence to make mail sending work again with POP3 and IMAP protocols from the blacklisted IPs I had to set in the Qmail install to not check the xx.xx.xx.xx IP against mail blacklisting databases.

On qmail install disabling an IP check in RBLSMTPD is done through editting /etc/tcp.smtp and following recreate of /etc/tcp.smtp.cdb – red by qmailctl script start.
The exact line I put in the end of /etc/tcp.smtp to disable the RBLSMTPD check is:


Further on to recreate /etc/tcp.smtp.cdb and reload the new cdb db records:

qmail:~# qmailctl cdb
qmail:~# qmailctl restart

Onwards, the IP blacklist issue was solved and all office computers from xx.xx.xx.xx succeeded in sending mails via SMTP.

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How to fix “sslserver: fatal: unable to load certificate” Qmail error on GNU / Linux

Friday, October 14th, 2011

After setupping a brand new Qmail installation following the QmailRocks Thibs Qmail Debian install guide , I’ve come across unexpected re-occuring error message in /var/log/qmail/qmail-smtpdssl/ , here is the message:

@400000004e9807b10d8bdb7c command-line: exec sslserver -e -vR -l -c 30 -u 89 -g 89
-x /etc/tcp.smtp.cdb 0 465 rblsmtpd -r -r -r -r qmail-smtpd /home/vpopmail/bin/vchkpw /bin/true 2>&1
@400000004e9807b10dae2ca4 sslserver: fatal: unable to load certificate

I was completely puzzled initially by the error as the sertificate file /var/qmail/control/servercert.pem was an existing and properly self generated one. Besides that qmail daemontools init script /service/qmail-smtpd/run was loading the file just fine, where the same file failed to get loaded when sslserver command with the cert argument was invoked via /service/qmail-smtpdssl/run

It took me quite a while to thoroughfully investigate on what’s wrong with the new qmail install. Thanksfully after almost an hour of puzzling I found it out and I was feeling as a complete moron to find that the all issues was caused by incorrect permissions of the /var/qmail/control/servercert.pem file.
Here are the incorrect permissions the file possessed:

linux:~# ls -al /var/qmail/control/servercert.pem
-rw------- 1 qmaild qmail 2311 2011-10-12 13:21 /var/qmail/control/servercert.pem

To fix up the error I had to allow all users to have reading permissions over servercert.pem , e.g.:

linux:~# chmod a+r /var/qmail/control/servercert.pem

After adding all users readable bit on servercert.pem the file permissions are like so:

linux:~# ls -al /var/qmail/control/servercert.pem
-rw-r--r-- 1 qmaild qmail 2311 2011-10-12 13:21 /var/qmail/control/servercert.pem

Consequently I did a qmail restart to make sure the new readable servercert.pem will get loaded from the respective init script:

linux:~# qmailctl restart
* Stopping qmail-smtpdssl.
* Stopping qmail-smtpd.
* Sending qmail-send SIGTERM and restarting.
* Restarting qmail-smtpd.
* Restarting qmail-smtpdssl.

Now the annoying sslserver: fatal: unable to load certificate message is no more and all works fine, Hooray! 😉

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