Learn how different email providers resend failed emails.
Upgrading from Lite to Pro
Learn how to upgrade from WP Mail SMTP lite to a paid license.
Setting a Custom Email Header
Learn how to add a custom email header to messages sent from WordPress.
Using Single Tenant With the Outlook Mailer
Learn how to use a specific tenant ID when communicating with Outlook's API from WordPress.
Debugging Sending Issues
Learn how to use Debug Events to resolve issues with your emails.
Understanding Email Delivery Status
Learn how to interpret the delivery status icons in WP Mail SMTP.