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Applications: Microsoft Active Server Pages 3.0, Microsoft Visual Basic 6.0
Operating System: Microsoft Windows 2000
As Web applications have continued to become more sophisticated and more interactive, the sending of email messages from Web pages has become a more important and central requirement of these applications. Mass mailings, in particular, are becoming more prevalent in today's Web-based businesses. just think of all the Web portals that offer subscription-based email lists. Oftentimes, these mass mail applications are written as stand-alone desktop applications; however, there are some advantages to building such an application with Active Server Pages. Probably the main advantage is the ability to launch a mass mail process from any Internet-accessible computer. But, for performance reasons, ASP can benefit with a little help from Visual Basic. In this article, we'll talk about the challenges of building a mass mail system and outline an approach that should work for most modest applications.
Solution at a glance
We'll start with a look at how you might accomplish building a mass mail application using straight ASP. Next, we'll build an analogous application using a Visual Basic middle-tier component and calling it from ASP. Then, we'll compare the performance of these two approaches. We'll close with a look at some of the limitations of this technique for very high-volume applications and offer a few suggestions and thoughts on where to go from here.
The key ingredients of a mass mail system
A mass mail application typically requires three ingredients: email addresses, an email engine, and the application code that drives putting the two together, as illustrated in Figure A on the cover. The addresses usually come from a database. We'll use a SQL Server database, but with only the smallest of code changes, you can use Microsoft Access, Oracle, Microsoft Excel, or just about any other data source you like.
For an engine, we'll use the SMTP Service built into IIS 5.0. Note that the SMTP Service isn't installed by default; you must explicitly select it. If you don't see an SMTP Virtual Server node in the Internet Services Manager, you'll need to install SMTP yourself. Again, you can substitute another email engine if you prefer. Other likely candidates are Microsoft Exchange/Outlook and Lotus Domino / Notes.
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