User cannot send out emails after migration #550 5.7.1 Delivery not authorized, message refused ##


A user recently reported that he cannot send emails after a recent email migration.

Whenever he tries to send an email it tells him the delivery has failed or was undeliverable because of "Security Policies" and #550 5.7.1 Delivery not authorized, message refused ##

I am still attempting to gather more information from the user, especially what exact email addresses he is sending to when he gets this error.  

The user also has attachments with each of the failed emails.  I will find out more about this as well, as that could be related to the issue.

Apologies if I'm a little vague.  Just wanted to ask if anyone has a guess.

Any help is appreciated.  Thank you.
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You probably need to recreate the connection to the Exchange server in Outlook. If you just changed the server name in the mail account setup dialogue box that can happen.

Just delete the mail account, reboot and add it back in. Make sure you accept the default option for cached Exchange mode. (How to to this, see here

If it still not work, try to create a new outlook profile (How to do it, see here

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