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Thread: DomainKeys / Digital Signaure to avoid Yahoo! Bulk Mail

  1. #1
    Kirkaiya's Avatar
    Kirkaiya is offline Senior Member
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    Default DomainKeys / Digital Signaure to avoid Yahoo! Bulk Mail

    I have two Zimbra servers running - in both cases, there is an MX record and A name record in DNS for the two domains (although a reverse-lookup on IP address for one of the servers gives the machinename.hostingProviderDomain.net rather than the machine's hostname).

    Sending and receiving mail is fine for both (albeit I'm having unrelated issues with logger, av & antispam on the 64-bit OS).

    But - mail sent from either domain to a Yahoo! email address (any address of the form @yahoo.com) ends up in that user's bulk-mail folder, until they open one up and click "Not Spam" in Yahoo.

    Digging deeper into Yahoo's treatment / categorization of spam, they have implemented a digital signature system, called "DomainKeys", and mail that isn't signed using this public/private key system is marked as spam. They list postfix as being one of the mail apps having an implementation of DomainKeys, and give the URL http://jason.long.name/dkfilter/ for more info.

    Soo... has anybody else experienced Yahoo! putting mails from a zimbra server into bulk mail?

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    KevinH's Avatar
    KevinH is offline Expert Member
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    Interesting. Might be based on your source IP as well. Doesn't seem to effect us as we can send to yahoo without trouble.
    Looking for new beta users -> Co-Founder of Acompli. Previously worked at Zimbra (and Yahoo! & VMware) since 2005.

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    jfriend is offline Starter Member
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    I have experienced this in the past and the problem has been due to reverse DNS not resolving on your mail server's IP address. We've also had the same thing sending to AOL users. Ensuring that there is a sensible reverse DNS entry for your server should resolve this. If you don't have the reverse records authoritative on your DNS server then you'll probably need to speak to your ISP about setting the record for you.

    Hope this helps.

    Jonathan

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    bbska is offline Active Member
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    What kind of line are you hosting your server on? Most business grade lines are OK. AOL and Yahoo! mark mail as spam if it comes from machines on DSL and Cable nets due to high volumes of spam email orriginating from them.

    if that's the case you can always set your outbound server to relay through your ISP's mail server , or contact the ISP to attempt to set up the reverse records.

    you shouldn't have a problem if you're on a T1 or higher line.

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    Kirkaiya's Avatar
    Kirkaiya is offline Senior Member
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    Quote Originally Posted by bbska
    What kind of line are you hosting your server on? Most business grade lines are OK. AOL and Yahoo! mark mail as spam if it comes from machines on DSL and Cable nets due to high volumes of spam email orriginating from them.
    In both cases, the servers are hosted in datacenters - one is with a managed hosting provider in PA, the other is a quasi-government colocation facility in Bangkok, Thailand, which is in the same building as the main telecom provider (in what is called the "CAT Telecom building".

    I've done some reading on Yahoo!'s "DomainKeys" program, and there are instructions for integrating it with postfix, maybe that's something I'll test out on a test machine. For the few Yahoo! mail accounts we've sent to that put the mail in the bulk folders, when the headers are examined, they show that reverse-domain-name-lookup passed fine, but that the "DomainKeys" authentication is "neutral".

    Maybe the server in Thailand is having issues just because it's in Thailand (the datacenter we're in Bangkok using has carrier-grade fiber connections to the government-owned gateway, so it's not due to a cable/adsl problem).

    I'll do more digging, if I find anything I'll post it here. Thank you for the replies and suggestions!!

    Update - no problems with Hotmail or AOL, however - mail sent to several accounts of each did not end up in their respective spam folders
    Last edited by Kirkaiya; 04-12-2006 at 06:50 AM. Reason: Additional info

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    sjobeck is offline Active Member
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    Lightbulb

    I have been working on mail filtering for the last 6 years and built a number of boxes to act as gateways/relays for clients incoming mail (and even a few outbound mail gateways as well to filter what employees are sending out) and have tried locking-down as many things as possible to decrease spam (as have we all, I know) and it is appearing that SPF is not really taking off like we had all hoped, which is a shame, it is very easy & very good. It looks like Domain Keys has a chance of being very important. I would like to see Zimbra integrate Domain Keys in to a future release. I understand that it is complicated though. Sysadmin's will need to run through a few steps, wihch are not hard, but you do need to read carefully & following instructions well. Finally, you need to publish your key in to your public DNS as a TXT record. It is worthwhile. I hope to see it soon. We really like Zimbra a lot. Thanks all. Peace.
    Thanks very much.

    Peace. Love. Linux.

    Jason Sjobeck
    xmpp:jason@sjobeck.com
    *Asterisk Consultant To The Stars *

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    freshfitz is offline Active Member
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    Default Whitelist on yahoo

    We had to fill out a form found somewhere in yahoo email support for them to whitelist our ip address then the mail stopped going to the junk folder when we sent to yahoo. We just had a change of ip addresses now our email to yahoo is going back to the junk folder

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    jholder is offline Former Zimbran
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    Many ISPs/MSPs check reverse lookup records. If you don't have one of those, then you're gonna be in trouble.

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    freshfitz is offline Active Member
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    how do you set up a reverse lookup record?

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    phoenix is online now Zimbra Consultant & Moderator
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    Quote Originally Posted by freshfitz View Post
    how do you set up a reverse lookup record?
    You probably need to ask your ISP to do it. Some details here.
    Last edited by phoenix; 04-19-2007 at 03:46 AM.
    Regards


    Bill


    Acompli: A new adventure for Co-Founder KevinH.

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