Agencies often face challenges such as maintaining high deliverability rates, managing multiple client accounts, and keeping up with evolving regulations. To overcome these challenges, agencies should invest in reliable email marketing software with robust deliverability features and multi-client management capabilities. Regularly cleaning email lists and implementing best practices for email deliverability can help maintain a good sender reputation. Staying informed about industry regulations, such as GDPR and CAN-SPAM, and ensuring compliance can prevent legal issues. Additionally, agencies should continuously educate themselves on the latest email marketing trends and technologies to stay competitive and deliver the best results for their clients.