http://www.joshuawinn.com/huge-email-delays-on-rackspace-cloud-sites-dont-use-php-mail/ is worth reading.

Delay is normal for email systems and it seems folk today want email but instant message speed. I can not guess how long you've been around (I'm from the days of the GE 210 if you must ask.)

That link is worth reading since rackspace responded.

OK, my comment. If you are a spammer, then you will not want to go with any of the names. They spot your activity and you are in worse shape than before. And I purposely set aside my feelings about spam.
Bob