ERROR: PleskUtilException - mailmng failed: Starting postfix: [FAILED]

Getting the following error after an upgrade to plesk 9.0 from plesk 8.6. when trying to start up postfix stmp

The plesk kb doesn't work.

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http://kb.parallels.com/en/5798
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0: /usr/local/psa/admin/plib/class.MailManager.php:226

MailManager::execWithException(string 'smart_exec', string 'mailmng', array, array, string 'lst')

1: /usr/local/psa/admin/plib/class.MailManager.php:258

MailManager->callMailManager(string 'start-service', array)

2: /usr/local/psa/admin/plib/class.MailManager.php:966

MailManager->smtpControl(string 'start')

3: /usr/local/psa/admin/plib/class.ServiceControl.php:420

ServiceControl->action()

4: /usr/local/psa/admin/htdocs/server/restart_services.php:17

require(string '/usr/local/psa/admin/htdocs/server/restart_services.php')

5: /usr/local/psa/admin/htdocs/plesk.php:41

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UPDATE:

k so it looks like you can do what a kb has mentioned.

http://kb.parallels.com/en/5801

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You may switch MTA using autoinstaller script.

Run the script without parameters

~# /usr/local/psa/bin/autoinstaller

and select Parallels Plesk Panel 9.0.0 (currently installed) on the fourth page. Disable all other applications like SSO and Sitebuilder.
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Let me know if works for you all! :)