Thanks for that info Ray.
I run my own server so the limitation is set by me :)
I am glad to hear that no bottle neck will come from UE. Now it's a matter of making sure that the mailings do not result in black listing.
Then on to the automation. I really do not want a bunch of my clients clicking all day long sharing my mail server, and having to deal with these surges. Tests are in order I guess to see what impact 100 emails all sent at once do to a server.