If they don’t answer within a few hours I don’t do business with them.
As far a mail companies go. I want complete stats, down to retrieving all subscribers who clicked on a particular link, all the links a particular person clicks on, and I have it set up so I know the games they like to play etc. That allows me to totally target each mailing to exactly those I know will respond.
There are all kinds of other stats at mailermailer, but these drill downs I would not live without.