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Showing posts from August, 2009

Greylisting in IndiMail

Greylisting is a method of defending email users against spam, by temporarily rejecting any email from a IP/Sender which it does not recognize. As per SMTP, the originating server should after a delay retry. A server implementing greylisting should accept the mail if sufficient time has elapsed. If the mail is from a spammer it will probably not be retried since a spammer goes through thousands of email addresses and typically cannot afford the time delay to retry.

IndiMail 1.6 onwards implements greylisting using qmail-greyd daemon. You additionally need to have the environment variable GREYIP defined for the qmail-smtpd process. The environment variable GREYIP specifies on which IP and port, qmail-greyd is accepting greylisting requests. qmail-smtpd uses UDP to send a triplet (IP+RETURN_PATH+RECIPIENT) to the greylisting server and waits for an answer which tells qmail-smtpd to proceed ahead or to temporarily reject the mail. qmail-greyd also accepts a list of whitelisted IP address…

Creating Self-Signed Certificate for TLS/SSL encryption

If you have installed indimail using any of the RPM at

you will get IMAPS, POP3S, SMTPS services installed by default. However Certificate are not installed by default. You may want to study the following google search. If you have not installed IndiMail using the RPM, then you can use svctool to create the IMAPS, POP3S, SMTPS services. Executing svctool without any option will give you a help screen.

You can save yourself a lot of trouble by using svctool to create self-signed certificate for IMAPS, POP3S, SMTPS (or starttls in smtp)

# /var/indimail/svctool --postmaster=postmaster@yourdomain --config=cert

You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank. For some fields there will be a default value, If you just hit Enter, the field will be left…