1 . Deactivate all the plugins and then check if the mail is working.
 
In case emails get through, it is most likely that the emails are not getting sent because of a plugin conflict.
Reactivate the plugins one by one until you find the one causing the issues.
You can now either delete it or look for an alternative.

2. Check if the issue is  caused by the server where you are hosting your site. You can use any of the following plugins.

https://wordpress.org/plugins/check-email/
https://wordpress.org/plugins/wp-test-email/

If you can send an email with the above tools and you cannot using the form, please open a ticket with us.

If the test email is not working then you can follow the following point.

3. Install the following plugin https://wordpress.org/plugins/wp-mail-smtp/ and try sending an email.
 
In case the e-mail is getting sent, please open a ticket with us
In case the e-mail is still not being sent and delivered, then you can move to the final step.

4. If none of the steps above work, it is highly likely that there is a problem with your host.
 
We would first recommend to contact your hosting provider and ask them to check the email configuration.
If they can't help you, please let us know.