Outgoing Listing-Mail stucks in Spam-Filter since

Question

Following Problem: I have written a mailing-list via PHP, SwiftMailer and Postfix. On my Old server it worked without any problems, but Since I moved to another Server (Exactly same configuration, but other IP) the list-mails stuck in the Spamfilter of the Receivers. (Espacially in Google Mail)

Is there anything I have to do escept rerouting the URL DNS-Records, that Google sees, that "I am that Server" and the mail is no spam?

Answer 1

First, check that your outgoing mail server is identifying itself correctly in the HELO command (or EHLO command) when it connects to a receiving mail server. There should also be an A record for this name that should point to the IP address of the mail server. Also, this IP address should reverse to some name (possibly, but not necessarily, the same name as above), and this name should point to the mail server's IP. If any of this is not right, then most spam filters will not consider your server to be a 'real' mail server, and will most likely flag any message sent from your server as spam. This is how many spam filters block spam that originates from computers that have been taken over as 'zombies'.

Another thing to do is to check that you mail server IP is not on any blacklists. You can use MXToolbox for this: http://mxtoolbox.com/blacklists.aspx

Another thing you can do is use port25's verifier tool. This tool will spot any red flags that might be causing your messages to be flagged as spam. See http://www.port25.com/support/authentication-center/email-verification/ for more info.

Last but not least, you might want to setup an SPF record for the domain that you are sending these messages from, to indicate that the IP of your mail server is authorized to send mail from this domain. This will help a lot. For more info, see: www.openspf.org.