Github user olegz commented on the issue: https://github.com/apache/nifi/pull/710 @trixpan Well, I am not sure what that is (will be looking) and how reliable mailtrap.io is for such testing giving it's description "Fake smtp testing server. Dummy smtp email testing". I've tested it with few real servers (gmail, yahoo etc) and all is good. I am not dismissing that there may be a problem but let's make sure we are not chasing some dummy error in mailtrap.io.
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