Webserver sent mail more likely to be spam?

[Dabrowski]

I'm using a script that emails via the webserver, and in Yahoo!, it always goes to the Bulk (spam) folder. I understand that the email world is such that if an email isn't preemptively whitelisted, there's no telling what might happen. However, is mail sent from a webserver more likely to be filtered out? I have the reply to, name, email, everything set properly. There are no webserver-obvious items, of course the detailed headers might be confounding me.

Thanks.