Several online email delivery services can handle newsletters for over 2 million users. You can use Sendinblue for high-volume email sending. It offers scalability and advanced features like automation. Amazon SES is highly cost-effective for large-scale email campaigns. Mailgun provides robust API solutions for email delivery. ActiveCampaign excels in managing large lists with powerful segmentation. GetResponse offers strong tools for list management and campaign tracking. SendGrid ensures high deliverability rates for large email volumes. Mailchimp also supports large email lists with detailed reporting and automation. You should choose a service based on your budget and features for best results.