405 Not Allowed error from nginx

I installed and activated the WP SMTP mail plugin and configured it according to the document How to Get WordPress Form Notifications Using the WP Mail SMTP Plugin to work with Gmail. Then I went to the top of the configuration page selected Email Test. It hangs for literally several minutes before nginx server returns a 405 not Allowed error with no other information fo me to figure out what’s not allowed. Any ieas about what I need to fix?

Using WP SMTP Mail v 1.3.3 on WordPress 4.9.8

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• This topic was modified 5 years, 10 months ago by Jan Dembowski.