To avoid spam filters and maintain good email deliverability with Gmail and Google Groups, it is crucial to adhere to sending limits, which vary by account type (Gmail vs. Google Workspace), the specific Google service used (Gmail, Google Groups, Gmail API), and sender reputation. Strategies include cleaning email lists, increasing engagement, segmenting lists for personalized content, gradually warming up IP addresses, implementing email authentication (SPF, DKIM, DMARC), using a dedicated IP, and avoiding spam trigger words. For new accounts, sending limits are lower and increase as a positive reputation is built. Google documentation outlines these specific sending limits and suggests monitoring API usage.