Sitefinity CMS sends emails using a mechanism called Notification service. Notification service guarantees the performance of your website is not affected when sending large amount of emails and delivers scalability and failure protection. Emails and notifications are sent out as message jobs. Each message job is persisted in the database, including the subscribers the emails need to be sent to, the message template, email content, the sender profile to be used, and so on. Emails can be dynamically personalized, for example with subscriber properties, such as last name, title and so on.
Message jobs are running as background tasks thus the website UI is not affected. In addition, when sending large number of emails, Sitefinity CMS processes them in batches, to deliver scalability. Finally, if a message job fails, for example your website restarts in the middle of a running job, the progress on each job is logged and the next time your site starters the job is resumed or if there is more than one notification server, another server resumes the job.
Notification service provides API to manipulate mailing lists, subscribers, and message templates, initiation of message jobs, configuration of sender profiles and getting message job progress information.