- Set up email settings for your web server;
- Verify that you can send and receive email using php function “mail”;
- Check Stores->Configuration-> Advanced->System->Mail Sending Settings. Email Communication is enabled.
- Check Stores->Configuration-> Sales->Sales Emails->Order . Enabled is “Yes”.
I verified mailing process in Magento and got emails.
Let us know with details, if you are faced with the problem without 3rd party modules.