for practical reasons the portal needs to use a mail account that is hosted away by another ISP, from the Azure environment the portal is on.
connection strings like 'whuk7.whukhost.com:465'
Doesn't look like you can having tried the various client settings?
Look to configuration forum item. This was caused by inconsistent tech documents on Azure.
Found the problem, solution is Azure support this when there is a dedicated IP address resource attached to the web server.
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