I'd like to know if the following scenario is possible:

We have:

- 1 Zimbra server
- 1 DNS server
- 2 internet connections from different providers both with static ip addresses

What I want to do:

- All outgoing SMTP traffic goes out using Provider1 link
- All incoming SMTP traffic is received using Provider2 link

What I thought was:

To have two MX records in our DNS server:

Provider2. 60 MX 10
Provider1. 60 MX 20

My intention is to force incoming smtp traffic through Provider2 by setting the MX record with the highest priority (10).
For the outgoing traffic I can force it to use Provider1 by setting this in my firewall.

Is this possible?