Running Postfix on a hosted service?

[vr]

I'm exploring moving my small, non-SQL Postfix installation from a SOHO 
type server to an ISP... Cloud... or whatever marketing term you fancy.

I ask here because my own personal experience with Web companies has 
been dismal when trying to send legitimate email from forum topics or 
end-user subscriptions due to blacklisting, etc. My searches in the 
archives and on the web turn up few Postfix-centric results. Ideally I 
would like to find something in the Chicago U.S. area but would consider 
others.

I'm looking personal experience, off list is OK too, as to a provider 
that's been more favorable for a Postfix deployment?