Good morning all, I searched and couldn't find an answer to the following question.
We have our Exchange server 2010 in house, which was set up before I came to the company. Last week we got another internet provider (Comcast) as a failover incase our fiber goes down, which it did this morning.
My question is how can I set up Exchange so if our primary connection goes down, and fails over to the secondary, emails will still go back and forth without any issues. I was reading about just adding another mx record which I thought I did correctly but no emails flowed through.
Our A records look like mail.mycompany.com 1.2.3.4 with mx record mail.mycompany.com (10)
Do i need to add another A record like mail1.mycompany.com 5.6.7.8 with mx record mail1.mycompany.com (12) These settings are all hosted with network solutions, so i am assuming that is where I need to add the info and not the Exchange server located here?
Best Answer
The best way to accomplish this would be from the firewall. Set up an interface for both ISPs with a different mx pointing to the respective public IP. Add a SNAT rule for port 25 to the Exchange server from both external interfaces (two separate rules). You are right that you will need two MX records, and the secondary should be a higher priority than the primary. Now without configuring failover for your firewall(s) then it's still a single point of failure, but firewall HA is a different beast entirely.
To avoid getting put on blacklists and other sending issues (ie remote smtp server refusing connections,) you should have your ISP create a reverse record (PTR) for your secondary IP. If you use a service like No-IP or DNSPark as your DNS provider you may be able to do it yourself, but it's best to have the ISP do it.