What is the best way to send large batches of emails in ASP.NET?
I'm currently looping through a datareader and calling the System.Net.Mail.SmtpClient's Send() method. The problem with this is that it's slow. Each email takes about 5-10 seconds to send (it's possible this is just an issue with my host). I had to override the executionTimeout default in my web.config file (it defaults to 90 seconds) like this:
<httpRuntime executionTimeout="3000" />
One caveat: I'm on a shared host, so I don't think it is possible for me to send using the PickupDirectoryFromIis option (at least, it gave me errors when I turned it on).
You could send the mail asynchronous. That way the timeout should not interrupt your sending.
This article should help you get started with that: Sending Emails Asynchronously in C#.
There is another approach here: http://www.vikramlakhotia.com/Sending_Email_asynchronously_in_AspNet_20.aspx
And off course there are several commercial clients available, but the only one that i have tried and can recommend is http://www.aspnetemail.com/
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Definitely spawn it off on a background worker process so they go out asynchronously.
BTW, 5-10 seconds per e-mail seems way slow to me. On my server it takes just fractions of a second per e-mail.