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I have some problems with my postfix setup. We send newsletter regulaly to our customers once or twice a week. and we have expierenced that many customers do not get their emails, it's simply because our domain has been listed as spammer in their spamfilter.

I've asked one of our customers to check what's the reason that our emails come directly in their spamfilter. he said "the problem is, that we are sending emails from a server which is not registered to be a valid exchanger for domain name [ourdoman].com".

can anyone explain to me what does this mean?

the company use MS exchange as our main mail server. and we use linux / postfix / php to send newsletters. both ms exhcange and postfix share the same domain name.

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marked as duplicate by Jenny D, cole, Dave M, kce, voretaq7 Nov 22 '13 at 19:06

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

    
It is probable that the domain uses DKIM/SKEY and that your postfix server is not included in those records. You should talk to the DNS admins to check what records are in place and have your server added. –  Jenny D Nov 22 '13 at 14:34
    
If my hostname in postfix is called new-webserver, which make my full qualify domain name to be new-webserver.mydomain.com. can I then send emails to customers as newsletter@mydomin.com, or should I send emails out as newsletter@new-webserver-mydomain.com?? – Zhenyu 9 secs ago edit –  Zhenyu Nov 25 '13 at 9:41
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Not necessarily. You need to read up on SPF and DKIM, and also read the question linked in on the top here (serverfault.com/questions/48428/…). This issue is a lot bigger than can be answered in a comment here. –  Jenny D Nov 25 '13 at 14:29

3 Answers 3

up vote 1 down vote accepted

Maybe you have not set a valid ptr-record for your mailserver. the myhostname entry in main.cf should be the same as your ptr record for your mailserver ip. Also check if you have a SPF-record for your domain. If so check if you have listed your postfix mailserver in it.

this statement

"the problem is, that we are sending emails from a server which is not registered to be a valid exchanger for domain name [ourdoman].com"

is quite wrong. A mailserver does not have to be the MX in order to be able to send email for that domain.

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Also if you're using a dial up connection with a dynamic ip-address you should consider configuring your Exchange server and postfix to use a "real" mailserver for sending out emails instead of delivering them themselves. As in case of a dynamic ip-address you will not be able to meet the requirements mentioned above. –  lsmooth Nov 22 '13 at 18:05
    
thanks for you answere. but if my hostname in postfix is called new-webserver, which make my full qualify domain name to be new-webserver.mydomain.com, can I then send emails to customers as newsletter@mydomin.com, or should I send emails out as newsletter@new-webserver-mydomain.com?? –  Zhenyu Nov 25 '13 at 9:40
    
you can use newsletter@mydomin.com, the myhostname has nothing todo with the sender address –  ah83 Nov 25 '13 at 16:18
    
Hej, another question. my webserver has different ips for incoming and outgoing. which IP should I use in PTR record. the incoming one or the outgoing one? thanks... –  Zhenyu Dec 5 '13 at 9:11
    
Use the outgoing. –  ah83 Dec 5 '13 at 12:15

You need to form correctly the headers and try good words in the content of your messages.

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Perhaps you could also include examples of what you mention in your answer in order to provide clarification. –  squillman Nov 22 '13 at 17:12

If that's truly the issue then you need to make a change to the MX record at the DNS server(s). More info here.

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