Modern Theme : Messages not sent from one Dashboard to another

Check the following : Go to WP Admin - Settings - BuddyPress - Components and make sure the Private messaging component is enabled. The "message" will trigger a BuddyPress message, so the user will receive the message in their Profile - Inbox section. This BuddyPress message in turn sends the email to the respective recipients, unless the recipients have explicitly disabled email from their profile - Settings - Emails section. If the issue is specifically related to emails, then : Are other emails working fine in your setup ? Try sending a direct message (Profile - Message -Compose) to a recipient and check if the recipient receives an email. If the setup is unable to send emails, then the issue would be with your web hosts SMTP  server. To confirm this I would recommend you to use  WP Mandrill plugin : https://wordpress.org/plugins/wpmandrill/ This would re-route your emails via mailchimp servers instead of your web hosts SMTP servers. Steps : a. Create an account in Mandrill (by mailchimp) b. Generate API keys in setttings. c. Install the WP Mandrill plugin d. Add the api keys in above plugin settings. e. Check the emails.