How to send internet mail with this configuration?

Hello, this is my situation:

Server A —> domain A

Server B —> domain B

The server B is the server that can send internet mails

What configuration should I configurate in the Server A to send internet mail throught server B?

When I try to send a message appears a DNS connection error on server A

Thanks

Subject: How to send internet mail with this configuration?

hi,

did you add server b with the ip in the configuration of server a as relay host for leaving the local internet domain???

ines