We have scripts we use to send emails to our exchange server, when we have it automate the messages, it randomly drops them, right now we are using ping and sleep (depending on scripting language) to add some delay to prevent this from happening.
Using Exchange 2010 and a Sonicwall, pretty sure its not the Sonicwall but the Exchange prevent it from excepting the messages, they are tiny messages, just a line or two of text.
Any idea how to turn this off, or add exceptions? Or what feature is stopping the messages?