We recommend not using server mail for your site emails. Instead, you should consider using Sendgrid, Sparkpost or some other transactional mail service. This tutorial will show you how to set SMTP settings for your mail needs, whether using your server SMTP or transactional mail. Our example is with Sparkpost but we recommend Sendgrid as we have reports that Sparkpost is restricting Social Network mail.

Clear your site cache and test.