Flyspray

I assume 192.168.0.10 is the address of another server, not the IP of the server with Flyspray?

Maybe this?

I googled Permission denied #13 and this is the first hit:
https://wiki.apache.org/httpd/13PermissionDenied

(13)Permission denied: proxy: HTTP: attempt to connect to 127.0.0.1:8080 (localhost) failed

This error is not really about file permissions or anything like that. What it actually means is that httpd has been denied permission to connect to that IP address and port.

The most common cause of this is SELinux not permitting httpd to make network connections.

To resolve it, you need to change an SELinux boolean value (which will automatically persist across reboots). You may also want to restart httpd to reset the proxy worker, although this isn't strictly required.

# setsebool -P httpd_can_network_connect 1

For more information on how SELinux can affect httpd, read the httpd_selinux man page.

It seems CentOS v7 changelog ( https://wiki.centos.org/Manuals/ReleaseNotes/CentOS7 ) tells something about SELinux changes:

Known issues
SElinux received major changes in this release, which might break certain functionality on your system.

My problem is solved. I have just typed this command line : setsebool -P httpd_can_network_connect 1
Then I tested the mail notification on flyspray and I received the mail in my mailbox.
In the case SMTP server I typed the FQDN (server_name.domain.fr) of my mail server.

Thank you so much for your help !