SMTP is a very chatty protocol which requires a good deal of talking between the client and the server. This talking, keeps a connection open on the port and IP that you are sending from, and since the connection is open and actively talking the thread is locked up until the client or server sends the session.

I said I would get back to this earlier, with the SMTP protocol it allows you to send multiple messages per connection, I am not talking about a bunch of CC requests, you can actually send completely different messages over the same connection and thread as long as the recipients are the same domain, but the SMTP client has to be intelligent enough to keep the connection open and do this. The .NET client isn’t.

There are ways around this problem, the biggest one is latency between the client and relay server, if you reduce that to near zero, you will have a very quick sending experience. A relay server is what ever you send your mail through. So if you send your mail through Gmail, smtp.gmail.com is your relay server, if you send your mail through Exchange, Exchange is your relay server.

The best way to reduce your latency to zero is to run an SMTP relay on your server. The SMTP relay will receive the messages from your application and then manage all these connections, this works really well for connections with high latency. It is very easy and takes almost no work, because you just install the built in IIS SMTP server, or if you want to use an external sender like Exchange you just hook the IIS SMTP server up as a smart host.

http://coderjournal.com/2010/10/easy-mail-delivery-with-smtp-smart-host/

Hope this helps.

I went back and an currently doing a masters in astrophysics.

I do not plan to use these skills directly, but its damn fun learning them!

I’ll leave note as I’m waiting for the ‘sql server 2008 service pack 1’ to download. In the background I have the Science channel on. Gee, only 65% downloaded so far.

I went to University of Houston and major in computer science. Actually I enjoyed the course work. Started work at American Airlines as a TPF assembler programmer. After 18 years of ‘Load address branch to solution’ I seque into C# and web developement on the .NET Framework. Currently, I am working for the State of Nebraska, Department of Natural Resources as a web developer.

bill

I too came from highly mathematical courses and went into development. But I missed the act of learning at university so much I decided to go back part time.

While these courses may not be relevant they are extremely useful in regards to the skills that are learnt, as I am sure you know…