authentication and relaying

How do I deal with a mail server that requires a sender to authenticate themselves in order for a message to be accepted? Are there settings in the "from email" setup for entering a user name and password for authentication?

For instance, say I set up a test and the from email address is
And I send a campaign from that user to,, and

I expect the test emails would get to the yahoo and gmail accounts, but if the mail server at is set with strict settings to not relay and to drop mail from local users who do not authenticate themselves, the email to will get dropped by's mail server since will look like a spammer or nefarious relayer to it.

How would I deal with this issue to ensure email sent from a user at a domain and to other users at that same domain gets through? (for my own mail server which is set as above, or if a client I'm doing this for has a similar email server setup).


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