The answer to this question: http://wordpress.org/support/topic/plugin-contact-form-sorry-your-e-mail-could-not-be-delivered?replies=14
Posted 3 weeks ago #
Help me I've got same error and been trying to fix it but I'm kinda hopeless . Could some give me the exact steps on how to configure each plug in to work it properly. Thank you" -
You should install an extra plugin called WP-mail-SMTP and configure it. Afterwards you should send a test email from this plugin and you will see if the plugin logs have errors. If these are some erors, then it is necessary to fix it.