EASendMail consists of Mail and FastSender object. Mail provides the basic stuffs to compose and send email and FastSender provides the advanced features to send email with multiple threadings and very high performance.
If you are developing an email client, Mail object is recommended to you, the rich events enables your application showing the progress of sending email like outlook express. If you are developing a mail listing application, the FastSender object is definitely suitable for you, unlimited works threads enable your application sending email concurrently with the highest performance.
Mail object can only send an email each time it doesn't matter asynchronous mode or synchronous mode. And Mail object is based on Apartment-Threaded model, that means you can only use the object instance created in the same thread.
FastSender object can send multiple emails concurrently and it is thread-safe. That means you can use the same object instance in different threads. However, FastSender object doesn't have the email composition capability, it must use Mail object as the email composer and send the content out.
To learn more about FastSender object, please refer to Programming with FastSender.
See Also
Using EASendMail ActiveX Object
Registration-free COM with Manifest File
User Authentication and SSL Connection
From, ReplyTo, Sender and Return-Path
Digital Signature and Email Encryption - S/MIME
DomainKeys Signature and DKIM Signature
Send Email without SMTP server(DNS lookup)
Work with EASendMail Service(Mail Queuing)
Programming with Asynchronous Mode
Programming with FastSender
Bulk Email Sender Guidelines
Process Bounced Email (Non-Delivery Report) and Email Tracking
Work with RTF and Word
EASendMail ActiveX Object References
EASendMail SMTP Component Samples