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If you have a firewall, it is possible that the JEMHC System needs to be allowed to communicate with your mail host. We recently added a second IP address for outgoing connections (removing a single point of failure), we did blog . A blog was created about that (Updated public IP addresses for outgoing connections ) and it also shows up in the app (Blog) section. We duplicate the information here, if you are getting repeat sporadic work/no-work scenarios this could be a reason:
JEMHC outgoing IP addresses
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