Need some help with our PFsense firewall.

Hello,

Recently replaced our firewall with a PFSense, or at least have it ready to.

Everything is in-line and ready to go, when we swap it out devices can connect to the internet, everything looks fine internally. I sent out a test email out, and it makes it out just fine, however I'm not getting my replies back into the email.

Our setup is an Exchange server, with a Barracuda email security gateway. I am seeing the emails coming into the gateway, but they are listed as deferred from there. So it looks like they just make it to that point, but not from there to the exchange server.

Some things I've noted:
I can access OWA via URL externally, but not internally.
I can access OWA if I type the local IP internally (https://#.#.#.#/owa/)
Pinging mail.ourdomain.com resolves the correct IP address.
Outlook connects to exchange just fine.

I'm not very good with firewall rules and I'm limited on my understanding. This is giving me a headache, so I'm reaching out to you guys. Any ideas here? Between all the options listed in the PFsense, and the 1:1 NAT/Port Forwarding/Firewall Rules inbound/outbound/source and destination ports and IPs I'm just confused on what should be set here. I feel like an idiot right now.

I appreciate the help, thanks in advance. We're currently swapped back to the old one, and everything works at that point. I don't think it's a DNS issue, as everything stays the same there and all IPs resolve the same now when pinging the domains.

Thanks!