2011-02-21 Email and DNS

Too bad I understand so little about server administration. Maybe one of you out there can help? I have the following mail setup:

• mail to alex@emacswiki.org is resent to alex@gnu.org via some LDAP rule. At the time I saved the following info by the admins in a note to myself:

dn: mail=alex@emacswiki.org,ou=Mail,dc=thinkmo,dc=de
objectClass: mailAlias
objectClass: mail
mail: alex@emacswiki.org
mailDrop: alex@gnu.org

• mail to alex@gnu is forwarded to kensanata@gmail.com via an alias. This looks as follows:

alex@fencepost:~$ grep kensanata /srv/data/com/mailer/aliases
alex: kensanata@gmail.com

• I read my kensanata@gmail.com mail via the Gmail website or via IMAP on the iPad.

The problem is a mail I recently got from one of the admins. It said that an email to alex@emacswiki.org was forwarded to alex@gnu.org and resulted in mail.thinkmo.de (the mail server for the account “alex@emacswiki.org”) being added to a black list. Obviously the admins don’t like this.

They require me to take one of the following three steps:

The only part I understand is “stop forwarding”. This is difficult because of two reasons:

  1. the email address gets a lot of spam, therefore it needs to be filtered by Gmail – my spam folder contains over 2000 spam emails for the last 30 days
  2. the email address gets so much spam that having Gmail fetch emails for alex@emacswiki.de from the mail.thinkmo.de server didn’t work – the list of unfetched email just kept on growing

I don’t know how to whitelist the mail server, and I don’t know where to do it. And I don’t know how the mail server is wrapping the emails it forwards to alex@gnu.org, and I don’t know how to change it.

What should I do?

I get my DNS services from Gandi, and they offer “email redirection” – but I’m assuming that it has no effect if I provide an external DNS (ns1.thinkmo.de and ns6.gandi.net – I have no idea how I determined these two many years ago).

Any suggestion on what I should write my admins?



This sounds like it’s not the forwarding to GMail which is the problem, but the forwarding to gnu.org.

The people blacklisting seem to be the gnu.org peeps. They need to give you exhaustive information on

a) the email including full headers that caused them to blacklist the thinkmo.de mail servers b) how to avoid this happening in the future

My guess would be that you could change your emacswiki.org mailDrop to kensanata@gmail.com if you wanted to get rid of the double forwarding, which also will make debugging easier in the future.

– Harald Wagener 2011-02-22 06:18 UTC

Oh, I see that forwarding to gmail directly wouldn’t work now. The dangers of commenting on an article you can’t see.

– Harald Wagener 2011-02-22 06:21 UTC

I don’t get how the setup you describe and which sounds perfectly reasonable would result in the mailserver being blacklisted. Are we talking about one of the big global blacklists here or did the blacklisting take place at one of the involved mail servers only (as Harald suggests)?

Could the admins bullshitting you because they actually don’t have a clue?

I agree with Harald: let the first server forward directly to gmail instead of gnu.org should work.

Andreas Gohr 2011-02-22 08:20 UTC

Thank you both.

The admin gave me a link to the Passive Spam Block List, an “easy-on, easy-off blacklist that doesn’t rely on testing and should reduce false positives because any user can remove their ISP’s mail server from the list.”

I’ll try telling the admins to redirect to Gmail directly, even though I don’t understand how this will help. I would have to argue as follows: gnu.org automatically submits spam email to a black list, where as gmail.com will just flag it as spam without reporting it to anybody else. Therefore redirecting mail to Gmail is safer for the mail server than redirecting mail to GNU.

Obviously Gmail’s spam filtering remains an unknown, therefore redirecting to Gmail could result in more mail from our mail server or passing through our mail server being falsely identified as spam by Gmail. It just would take a much longer time to discover Gmail spam filters doing that, and it would probably be much harder to act against. Or I could just trust in Gmail’s superior filtering rules. :)

AlexSchroeder 2011-02-22 09:34 UTC

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