You could fix your email issues using Transaction ESP, like SendGrid. Install this plugin in WordPress https://wordpress.org/plugins/wp-mail-smtp/ Which switches all emails to use SMTP and you set it up with your ESP's SMTP credentials. I do this a lot with sites on cloud instances and it works very well. On top of that, using an ESP like SendGrid you can actually see statistics of who is getting the email, bouncing, opening, etc... Great stuff, especially for a online business.