ServiceDesk receives cant send e-mails.

I have ServiceDesk configured to send emails but, when the mail is to be sent to an outside mail address, it receives a mail informing that there was an error.

Sample notification error:

------------------------------------------------------------------------
Undeliverable: [Pedido N� : * 85=?UTF-8?B?ICpdIDogRXJybyBpcnJlY3VwZXJhdmVsIGdlcmFsIGE=?==?UTF-8?B?byBpbXByaW1pciBkb2N1bWVudG9z?=
Descri��o

Your message

To: info@alflora.com
Subject: [Pedido N� : * 85 *] : Erro irrecuperavel geral ao imprimir
documentos
Sent: Mon, 30 Jul 2007 19:27:36 +0100

did not reach the following recipient(s):

info@alflora.com on Mon, 30 Jul 2007 19:27:36 +0100
There was a SMTP communication problem with the recipient's email
server. Please contact your system administrator.
does not exist>

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My server requires authentication and I use the same account to send and receive, so I think the problem is not with the authentication.

I believe that the error is incomplete becouse it dont make sense.

Can you please help me.

Thanks