GAPPSSMTP is an email sending protocol used by Google Workspace (formerly G Suite) to send emails through their servers. It allows users to configure their email clients or applications to send emails using Google's SMTP servers.

Setting up a custom DKIM (DomainKeys Identified Mail) key for your emails involves adding an extra layer of security to your outgoing messages. DKIM adds a digital signature to your emails, which helps verify the sender's identity and ensures the email hasn't been altered in transit.

What is GAPPSSMTP and How to Set Up a Custom DKIM Key For Your Emails?

DMARC Report