[Plugin: News Mailer] Not sure what to say but….

https://www.ads-software.com/extend/plugins/configure-smtp/
https://www.ads-software.com/extend/plugins/wp-mail-smtp/

This is the plugin saying that you need to use SMTP. You don’t need to download any other plugins, just configure the SMTP-settings under Settings -> Mail.

1. Choose SMTP under Transport type.
2. Specify URL, Username and Password under SMTP. This requires you to have a SMTP mail server somewhere, however you can use Gmail for example as your SMTP. Google “gmail smtp settings” if you are unsure.