Seems like the problems with your configuration, please ensure you have configured SSL/TLS (as required by your Exchange server) and username/password correctly, see https://confluence.atlassian.com/fisheye/configuring-smtp-298976823.html . You may also need to enable basic authentication on the Exchange server.
If this still doesn't help take a look at the answer to similar question answered regarding JIRA configuration: Send email problem, Client was not authenticated. It seems Exchange needs to be configured correctly to allow Basic Auth.
Hope that helps,
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