1. Avoid Spam Triggers: Refrain from using excessive exclamation marks, all caps, or spammy phrases. 2. Sender Reputation: Maintain a good sender reputation by avoiding spam complaints and high bounce rates. 3. Unsubscribe Option: Always provide a clear and easy way for users to unsubscribe. 4. Consistent Sending: Maintain a consistent sending schedule to build trust with Gmail's filters.