Q2A uses a built-in version of PHPMailer, which (by default) uses PHP's inbuilt mail() function to send mail. This tends to use the host OS's default mailer - usually sendmail on unix-like systems.
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.