I have a small Ubuntu 16.04 VPS that's running nginx/php-fpm to run a Wordpress site, and running an SMTP server through Postfix/Saslauthd. My mail server is working just fine at sending and receiving mail, and I have Wordpress set up to use SMTP instead of php mail() through the Postman plugin and that works perfectly.
However, when attempting to submit an email contact form through Wordpress, I keep getting a 405 Not Allowed error. I tried a couple different contact form plugins (Pirate Forms, Contact Email Form) and still got the same result. I also disabled Postman to force Wordpress to use php mail(), but still got a 405.
Nginx debug logs here Nginx config here.
EDIT: URL I'm trying to post to is https://example.com/contact/
Nginx access log shows this:
xxx.xxx.xxx.xx - - [09/Oct/2016:20:10:07 -0400] "GET /favicon.ico HTTP/2.0" 200 524 "https://example.com/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/53.0.2785.143 Chrome/53.0.2785.143 Safari/537.36"
xxx.xxx.xxx.xx - - [09/Oct/2016:20:10:08 -0400] "GET /contact/ HTTP/2.0" 200 6090 "https://example.com/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/53.0.2785.143 Chrome/53.0.2785.143 Safari/537.36"
xxx.xxx.xxx.xx - - [09/Oct/2016:20:10:09 -0400] "GET /favicon.ico HTTP/2.0" 200 524 "https://example.com/contact/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/53.0.2785.143 Chrome/53.0.2785.143 Safari/537.36"
xxx.xxx.xxx.xx - - [09/Oct/2016:20:10:22 -0400] "POST /contact/ HTTP/2.0" 405 626 "https://example.com/contact/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/53.0.2785.143 Chrome/53.0.2785.143 Safari/537.36"
xxx.xxx.xxx.xx - - [09/Oct/2016:20:10:22 -0400] "GET /favicon.ico HTTP/2.0" 200 524 "https://example.com/contact/" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Ubuntu Chromium/53.0.2785.143 Chrome/53.0.2785.143 Safari/537.36"
Not getting anything in error.log.