I have configured a number of Atlassian products including JIRA, Confluence and Bamboo on a single server. I have configure the SMTP mail host in the same way for all three to use a gmail.smtp.com account.
Also all three applications are accessed via and https link which is then redirected using apache proxy_mod to the local app and port. This is working perfectly well for all apps on there. However, if I try to send a test email from either Confluence or Bamboo I receive a 502 Proxy error. No other email appears to be getting sent although there is nothing in the mail queue or in the mail errors.
Proxy Error
The proxy server received an invalid response from an upstream server.
The proxy server could not handle the request POST /admin/mail/dosendtestemail.action.
Reason: Error reading from remote server
Apache/2.2.15 (CentOS) Server at confluence.lucr.com Port 443