Yes, SMTPmail is well suited to send an email to thousands of recipients, particularly with its MassMail method. (Note: MassMail method is available in Full version of SMTPmail only.) SMTPmail also has the ability to drop messages off in a pickup folder so that the ASP script does not need to wait for the mail server to receive the emails before it can finish executing. Measuring how long a mass mailing takes, however, is somewhat difficult to calculate because of the many factors that fall outside the scope of SMTPmail.
The capacity and settings of the Web Server (that runs SMTPmail) and Mail Server (the server that receives the emails from SMTPmail and forwards them) play heavily into this equation. Another important factor to consider is the size and type of email being sent.
An informal test using the MassMail method reveals that 20,000 simply formatted emails dropped into a pickup folder takes approximately 2 minutes and 54 seconds. The specification of the web server: 1.6Ghz Pentium 4, 512 RAM, Windows 2000, IIS5 SP2 – Access 2002 database.