Just a note that I have moved this post to the appropriate category since the issue is not related to scanning or scan configuration. Also, please don’t post screenshots of terminal output or code. The Start Here guide is a good place to understand how to format text for the forum. Thanks kindly 
I think you will need to enable debug level error output to see if there are any failures during the sendmail command. You will find loggging config files in the /etc/gvm directory. To enable debug, open the gvmd_log.conf file and set the logging levels to 128. I think the [manage] level is the only one you need to escalate for this issue, but if that doesn’t work, raise all evels using the [*] at the very bottom.
You can also check the logs from the mail transfer agent application you have configured.