SMTP (Simple Mail Transfer Protocol) is an industry-standard for sending emails. Proper SMTP configuration helps increase email deliverability by using authentication.
Popular email clients like Gmail, Yahoo, Office 365, and Zoho constantly battle email spammers. One of the things they look at is if an email originates from the location it claims to be originating from.
If the proper authentication isn’t there, emails either go in the SPAM folder or, worst, don’t get delivered.
What You Get For Free
WP Mail SMTP free version is easy to set up and includes many email clients like SMTP.com, Sendinblue, Gmail SMTP (Gmail, Google Workspace, G Suite), Mailgun, SendGrid, Postmark, and SparkPost.
The pro version allows you to connect to Amazon SES, Microsoft SMTP (Outlook.com and Office 365), Zoho Mail, and all other SMTP.