Mikrotik and pfsense

Hi all

I desperately need help here. I installed a pfsense at the HQ of a company which has two branches using Mikrotik. At the HQ there is a Zimbra mail server. I have done all configurations properly on the pfsense but the branches are unable to access emails. When I remove the Mikrotik and put Green Packet emails are flowing without any problems. Is there an incompatibility between the two?

I’d say that not all configurations are done properly, or it would’ve worked.
But we’ll check our crystal balls regarding that.