It worked fine when I use a message template to test. Could you please change to another receive email address to test? sometimes emails will be filtered if account have words like test.
when you use message template as is without modification it's working fine, but when add picture or table the email didn't send.
Also, i use Gmail account in receiving test and i tried on other receiving emails and the same issue.
i make this modification on WelcomeMessage this test didn't received and on other one like NewForumTopic this test has been received "because it's just text without tables and pictures"