What is the most effective autoresponder message

the one that came from someone that had something i wanted and was giving it for free

I don't think there is a single "best" that works for everyone; people differ. I'm assuming you're looking at how to get people to open up all your emails; sharing my side of the story, this may not be what you're looking for.

Sometime ago I made a decision to check my email just once a day (the one for newsletter signups, that is); a few slip ups, but for the most part I've been able to stick to it. The downside is that when I log in, I have about 80 - 150 emails that have come in.

Here's how I decide what to read.

1) There are specific people who I do read, regularly (Paul Myers talkbiz, or Tony Shepherd); these get filtered to a separate folder automatically.
2) Other emails - I use a yahoo account, select the "unread messages" view. Now I click on select all, before browsing through the list
> Any repeat subjects (that indicate multiple marketers pitching the greatest new launch) stay selected for marking as read.
> Non repeating subjects, but having some kind of urgency "24 hours to go" also get marked as read.
> A few emails do have intriguing subjects that pique my interest; I uncheck these, to read; all the rest get marked as read.

Today's samples, for instance: email subjects that passed through to be read

1) Twitter tip below, and my best web audio software is...
2) It's not always about adding subscribers straight away
3) Backward thinking moves you forward?
4) Here's what I told Johnny about...

Over time; if I've opened up at least 2 or 3 emails from you within a week and found it good, or your name sticks in memory; your emails get upgraded to the regular folder, and THEN I read ALL your emails, including your pitches. The subject doesn't matter, nor does the fact that you're sending a pitch; you've won my trust.