Dear Foryourit,
I found you by doing a search on this topic of Multiple email servers connected your comment was. Below - and my question is can you do this for me ? Can you set up my email servers so they work together like you described ? Can you tell me who can do this for me ? I need them all to work in syc and need to have them set up properly.
Can you email me at joedeir@gmail.com I would like to talk to you on the phone about this also OK ? Please text me or call me 708-307-9777 I need someone to help me set up dual email -servers -as described in your comments below please help and/or direct me. We are a non profit ( soon ) and need someone to help us.

I want to have slaves email servers, in case one falls into a black list, just change the MX record and send the following server and so on.

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ForYourIT October 13, 2015
Allright, then you need to create multiple mail servers manually (for example with posfix and dovecot) and configure them properly with their own hostname.
After this you need to change your DNS MX/A/CNAME records. These will then handle the needed mailserver. Also make sure you have good PTR,DKIM,SPF records so your mailservers will work together properly

So what are the common settings to do this ? DNS ? MX ? A ? Cname ? and what changes in the the PTR ? DKIM ? SPF ? Where can I find this info ? If someone can please contact me and help our non profit setup. My info is above.