ssis package Failed to send email outside the domain

dear  i  have and issue regarding the SMTP Mail Task: Send Report

please note that when i tray to send email in side the domain  it successfuly run .

but the issue is when i trayed to send wmail outside OUR DOMAIN ,

i already used  authenticate check box. usinf a domain user.

but still i have the same issue .

below is the package log :

****************************************************************************************************
The execution of the following DTS Package succeeded:

Package Name: MOF_Registration_Info_fff_Credit_Bank
Package Description: (null)
Package ID: {8D9ED065-846F-4EC3-B9F1-E09546D655B1}
Package Version: {F3EC805F-FA10-4B48-8048-72231A92B7EB}
Package Execution Lineage: {3B9584B8-6734-4AC4-99DD-4AD2A8CF942F}
Executed On: hahaha-com
Executed By: ahmad
Execution Started: 10/21/2012 4:27:26 PM
Execution Completed: 10/21/2012 4:27:31 PM
Total Execution Time: 5.5 seconds

Package Steps execution information:

Step 'DTSStep_SDN.SMTPTask_1' failed

Step Error Source: Microsoft Data Transformation Services (DTS) Package
Step Error Description:The task reported failure on execution.
Step Error code: 8004043B
Step Error Help File:sqldts80.hlp
Step Error Help Context ID:1100

Step Execution Started: 10/21/2012 4:27:26 PM
Step Execution Completed: 10/21/2012 4:27:31 PM
Total Step Execution Time: 5.016 seconds
Progress count in Step: 0
Task Log for this step:
-----Start Task Log-----

Error = 1 (00000001), Description = DTS: Log initialized
Error = -2147220495 (800403F1), Description = SMTP Mail Task: Execute() failed
Error = 1 (00000001), Description = DTS: Log closed

-----End Task Log-----

Step 'DTSStep_DTSCreateProcessTask_1' succeeded
Step Execution Started: 10/21/2012 4:27:31 PM
Step Execution Completed: 10/21/2012 4:27:31 PM
Total Step Execution Time: 0.015 seconds
Progress count in Step: 0

Step 'DTSStep_DTSCreateProcessTask_2' succeeded
Step Execution Started: 10/21/2012 4:27:26 PM
Step Execution Completed: 10/21/2012 4:27:26 PM
Total Step Execution Time: 0.187 seconds
Progress count in Step: 0

Step 'DTSStep_DTSDataPumpTask_1' succeeded
Step Execution Started: 10/21/2012 4:27:26 PM
Step Execution Completed: 10/21/2012 4:27:26 PM
Total Step Execution Time: 0.282 seconds
Progress count in Step: 2
****************************************************************************************************

regards,,,,,