I just downloaded the free version of AVG Antivirus. I disabled the 'check outgoing mail', but all my send mail is [still] refused. What do I need to do to be able to send mail?

Error message:
This is the AVG E-mail Scanner program.

I'm sorry to have to inform you that the message returned
below could not be delivered to one or more destinations.

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<email address is here|>: Relay access denied
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Your e-mail message is being returned to you in the next part of this
message. Try to send the message again.

Should you need assistance, please contact your administrator or your
internet service provider.