outbound nat

If you have multiple WAN uplinks you need to configure a multipath rule. See interface menu, there are 3 examples too.

Best regards 

Alex 

thank you

i see the samples, but i can't understand from them. how can i "attach" a specific lan to a specific wan

You could specify a source in the multipath rule. (I didn’t had the case.)
Maybe the other way around. What destination or service do need this WAN? That works for sure.

i have 2 email servers behind the utm

i need 1 of them to go out via wan1

and the other via wan2

so both services are smtp, but the source is diferent 

maybe my problem is the smtp proxy module? maybe it's ignoring nat and pushing smtp out only with the default gateway of the entire utm?

OK. I think your problem could be solved by using a SNAT Rule. These are created under Network Protection -> NAT.
I'll show you one example which should fit your needs.

Put in the source one of your servers. The service and destination should fit.
Now specify in change source the public IP you want that server to send.
Please let me know if this is working for you.

Best regards

Alex

thank you

no, the traffic still flows via the main public ip

i'm guessing it has something to do with the smtp proxy

Then don't use the smtp proxy. The SMTP Proxy is an email server by itself. See ISO/OSI for differentiating SMTP or TCP. I think I don't have any further hints, so I'm out of this thread, sorry.

Good luck

Alex

If both mail servers are relaying outbound mail though the STP Proxy, they will both send from the IP of "External (Address)."  I'm certain there a suggestion to allow different public IPs and different interface in Ideas, but I don't think that on the horizon.  Your best bet is to combine Alex' suggestions and use a Multipath rule binding non-proxied traffic to another interface for one server.

Cheers - Bob