The problem, that it is not possible to send e-mails with em-client is really a job-killer. This must be solved urgently.
there are lot of issues at sides of specific servers causing the problems (either connection or security policy issues) that are needed to be workarounded. Please see the extensive topic https://discourse.emclient.com/emclient/to… for the solution and make the log I mentioned 5 month ago eventually, if the problem persists. Send the System.Net.trace.log file to firstname.lastname@example.org .