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How can I stop my mail from being catagorized as SPAM?

By rich.contreras ·
I have a mail server (Exchange 2003) that handles multiple Internet Domains for different Commercial services that we provide. When we send mail from this server to Yahoo, Gmail, and Aol clients our emails ALWAYS end up in the SPAM folder. I have checked with all the well known "Blacklists" and find that we are NOT on any of them. My server replys to a HELO Query with a hostname "mail.xxxxxx.com" our first Internet Domain. I have an A record in my DNS for this host and a PTR record that reverse resolves our IP to the hostname. I have a valid SPF record in my DNS for that Domain and in each of the subsequent domains authorizing this server to send mail for each Domain. I have a Domainkey private key installed in the Exchange server and a Domainkey public key setup in our DNS for each Domain and still we end up in the SPAM folders.
Is there more that I can do short of installing a seperate server for each Domain? Is there such a product that will send mail and reply to HELO Queries using a unique IP address depending on the domain of the email being sent so that each Domain can have a PTR and HELO Reply that matches the sending Domain of the email?

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Wow, a real head-scratcher question

by robo_dev In reply to How can I stop my mail fr ...

See this link:

http://serverfault.com/questions/158828/ptr-record-rdns-for-multiple-domains-on-a-shared-ip-address

If I understand it correctly, since you have one IP, but many domains, forward DNS works properly (from the mail recipient perspective) but reverse DNS would not??

http://www.amset.info/exchange/dnsconfig.asp

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Found another relevant page

by TobiF In reply to Wow, a real head-scratche ...

robo_dev sent me reading deeper.
Here's a page that may describe a workaround:
http://www.amset.info/exchange/smtp-connector.asp

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Reverse DNS works and shows the main Domain Hostname

by rich.contreras In reply to Wow, a real head-scratche ...

Actually Reverse DNS works and returns mail.MainDomain.com, but when I send mail from a user team@Domain2.com, in the header I see Return-Path <team@Domain2.com> and Received: from 127.0.0.1 (EHLO mail.MainDomain.com) (66.9.246.119).
Now even though I see the SPF and Domainkey Authentication PASS:
"Received-SPF: pass (mta1185.mail.mud.yahoo.com: domain of team@Domain2.com designates 66.9.246.119 as permitted sender)"
"Authentication-Results: mta1185.mail.mud.yahoo.com from=Domain2.com; domainkeys=pass (ok); from=Domain2.com; dkim=pass (ok)"

The mail still ends up as SPAM. I can only imagine that the issue is that Domain2.com sent it but using mail.MainDomain.com server. I have not heard back from anyone at Yahoo and Gmail has ABSOLUTLY no way to contact anyone that can shed any light on what Goggle Mail does.

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My thought is that your setup is perhaps

by robo_dev In reply to Reverse DNS works and sho ...

the way that spammers try to evade spam filters? Since it's obviously cheaper/simpler to host multiple domains from one IP, I would bet that is how it's done by the bad guys.

So, in effect, you need to discover the methods of the spammers in order to do what you need to do? :)

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MX

by TobiF In reply to Reverse DNS works and sho ...

For all domains, the MX record should point to the name mail.MainDomain.com
And reversedns should point back to this name.

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Outgoing and Incoming servers are different

by rich.contreras In reply to MX

Unfortunately we are currently using an External Service like Postini to filter out Viruses, Malware, and SPAM before it is forwarded to our mail servers so the MX Records relect these servers which are different than the servers that actually receive our Incoming mail or Send mail.

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