I have two network cards, the SMTP sends from working network card

I have two network cards in my server, and both of them are connected, one is connected local and other one internet,

I have crea开发者_运维问答ted a SMTP service, the problem is that the smtp only tries sending emails from the local network card.

I want it to try send emails from the internet network card, how can this be solved?

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SMTP does not know about network interface cards. The decisions is made by the operation system. What does your routing table look like, e.g. the output of "netstat -rn" on a Unix-like OS, and what is the IP address of the destination that your SMTP service tries to connect to?