==== Required information ====
- iRedMail version (check /etc/iredmail-release): ) 0.9.4
- Linux/BSD distribution name and version: CentOS 7
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Apache
- Manage mail accounts with iRedAdmin-Pro?
- Related log if you're reporting an issue:
====

Presently we operate a Exchange Server with 30 Domains. I have set the FQDN of the Server to mail.domain.com and added the 30 accepted domains into Exchange (domain.com, domain1.com, domain2.com etc...). At each ISP I have set the MX record of every domain to mail.domain.com and have the router port forward traffic to the Mail Server. Works with no issues.

MX  > mail.domain.com
A     > mail.domain.com. > 5.10.xx.xx

So how can I accomplish this with iRedMail as what I still havn't quite grasped here is where many of the DNS zone records would sit for multiple domains in iRedMail.

The CentOS server for example is called
FQDN: mail.domain.com
Hostname: mail

iRedMail has say 4 domains
domain.com, domain1.com, domain2.com, domain3.com

All domains will have ISP DNS records pointing to the mail.domain.com with ptr resolving to the Gateway IP. The router will in turn port forward on all traffic to the iRedMailServer. correct??

At the ISP
MX  > mail.domain.com
A     > mail.domain.com. > 5.10.xx.xx

So my question is where would I be setting the following records?

mail.domain.com => CNAME: domain.com

domain.com      => TXT *2 for DKIM and SPF
domain.com      => SPF
domain.com      => DMARC

Thanks for any pointers.. or suggestions.