*MY* outbound mail server for our nagios system (it delivers it locally to the machine's SMTP Agent) does not do batch mode. It also does *not* send out 150 messages, using 150 connections at the same time to the same MX records. Its purposely setup to do them all serially.

Sure, I sometimes get a few hundred messages in 15 minutes. But every single one of them is sent ... singly and one at a time to the same MX record.

Now, if my nagios server needs to send out messages to a few AT&T recipients, a few Verizon recipients, a few T-Mobile recipients and a few Rogers recipients all at once, there will be multiple mail drops happening at the same time to each MX, but serially for those MX records.

I guess, I thought through this a bit more than others, as I am the recipient of some Denial of Service attacks... I didn't want to be a perp.

Many people don't test and just assume things are good.

I also, once I have an incident... I turn off notifications... until the event is past.

I guess I'm not the norm.