Thanks for your help and reply. Your reply was very helpful. In the final analysis it doesn't seem to be a concrete5 problem but an issue with our server. This issue was not resolved but a work around was applied and the problem resolved. Thanks.
We were unable to configure our website host, Bluehost, to send emails generated in concrete5 and by using Thunderbird as a client and bluehost as an smtp server. The work around was not to use Bluehost.
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