Full article: https://support.google.com/a/answer/10036904?hl=en
"IMAP client link protection is available for iOS Mail, Mac Mail, Microsoft Outlook, and common Android mail clients.
When link protection is on for IMAP clients, clicking a link in a recent message starts a malicious link check. If no malicious links are detected, the recipient is taken to the destination. For older messages, a window might appear, and you can tap or click to open the link."