WAFDOF

I have an unusual issue that I believe it related to a setting in the IIS SMTP Virtual Server Settings.

I have an intermittent problem where an email sent by a small asp.net application would fail to send the exception was "Error receiving data from socket." The VB error message generated related to "The transport failed to connect to the server. "

I spent a bit of time troubleshooting the asp code only to have the same results...sometimes the emails would process and sometimes they would not.....no variable changed at all.

In an attemtp to find a pattern to the problem and rule out asp.net code I wrote a very small windows application that sends an email once a minute and reports back the results. I was amazed to find a solid pattern and this is where I could use some help pointing me in the right direction.

The sever sends an email once a minute and the first 9 emails send fine but the next 9 emails will fail to send and then the pattern repeats itself the next 9 emails go fine, then will send 9 emails that fail...etc.

Nothing changed in the settings...each email was sent using hardcoded variables so there would be no difference in the TO: FROM: SUBJECT: SMTP SERVER: or BODY.

I have run this for several hours always with the same pattern revealing itself, 9 times it will send email then 9 times it will fail then 9 times it will send and so on.

Now for the server details. This is a development server running behind out INTRANET firewall. All virus software has been disabled. The Firewall on the server has been disabled. The application is running ON the server. The situation manifiest itself both in using windows applications and Web pages (asp.net).

These are the current property settings of the virtual server:

IP Address is within the IP range of the intranet - 10.16.56.9
Connections limited to 100
connection time-out in minutes 5
Under advanced theIP Address and TCP Port are 10.15.56.9 25

Access tab - Anonymous access is checked
connection control as access granted to 10.16.56.9
relay restictions are granted to 10.16.56.9
connection control grrants access for 10.16.56.9 to the virtual server

Messages tab
Message size limited to 2048 KB
Session size limited to 10240KB
Limit number of message per connection to 100
Limit number of recipients to 100

Delivery tab
First realy interval minutes 15
Second retry 30
third retry 60
subsequent retry 240
delay notification 12 min
Expiration timeout 30 min
Loca delay 24 min
Expiration timeout 12 min

Outbound security set to anonymous access
Outbound connections limited to 1000
time-out 2 minutes
number of connections per domaim 100
TCP port 25

These settings have been changed a few times as I gleen what I can from the internet. I have stopped and started the the SMTP Virtual Server on variable changes without effect.

The TO: from: variables for the email are valid as they have been checked and email is actually sent and received using the same variables.

Obviously I am curious about the pattern I have discovered. Each minute an identical email is sent...and as I have said the first 9 times the email goes fine then the next 9 times it will fail and then the next 9 times it will go fine..and so on. I have not been able to find a variable in the SMTP porperties that is tied to this apparent 10 min cycle.

This server does not touch the INTERNET and the SMTP mail being sent stays within the intranet of our organization.

What additional information may be needed to look into the unusual circumstance?

WAFDOF