Hi,

I am using an installable php script which is both simple to use and quite powerful. It's delivery results to hotmail and gmail are very good. Haven't yet had an email go to the spam folder. It is a bit iffy with yahoo where a good percentage of the emails go to the spam folder. This is a full featured sequential responder.

It's one of the more useful responders I have found - free or paid.

you can download it here: http://infinite.ibasics.biz